U.S. patent number 11,287,196 [Application Number 16/428,582] was granted by the patent office on 2022-03-29 for helically baffled heat exchanger.
This patent grant is currently assigned to LUMMUS TECHNOLOGY LLC. The grantee listed for this patent is LUMMUS TECHNOLOGY LLC. Invention is credited to Sherif Elsayed, Richard John Jibb, Eric Drew Macedo, Melanie O'Sullivan.
United States Patent |
11,287,196 |
Macedo , et al. |
March 29, 2022 |
Helically baffled heat exchanger
Abstract
A heat exchanger including a shell having a longitudinal axis, a
plurality of baffles, such as elliptical sector-shaped baffles,
each mounted in the shell at a helix angle H.sub.B to guide a fluid
flow into a helical pattern through the shell. Each of the
plurality of baffles includes an outer circumferential edge, a
proximal radial edge, a distal radial edge, a proximal side, a
distal side, and a plurality of spaced apart holes that are
traversed by a plurality of axially extending tubes. Each of the
first plurality of seal strips is disposed from a proximal of the
plurality of baffles to a distal of the plurality of baffles.
Inventors: |
Macedo; Eric Drew (Houston,
TX), Jibb; Richard John (Houston, TX), Elsayed;
Sherif (Houston, TX), O'Sullivan; Melanie (Houston,
TX) |
Applicant: |
Name |
City |
State |
Country |
Type |
LUMMUS TECHNOLOGY LLC |
Bloomfield |
NJ |
US |
|
|
Assignee: |
LUMMUS TECHNOLOGY LLC
(Bloomfield, NJ)
|
Family
ID: |
73551401 |
Appl.
No.: |
16/428,582 |
Filed: |
May 31, 2019 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20200378697 A1 |
Dec 3, 2020 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28F
9/24 (20130101); F28F 9/0236 (20130101); F28D
7/16 (20130101); F28F 9/22 (20130101); F28F
9/0219 (20130101); F28F 2009/224 (20130101); F28F
2009/228 (20130101); F28F 2009/222 (20130101); F28F
9/0221 (20130101); F28F 2230/00 (20130101); F28F
2009/226 (20130101); F28F 2240/00 (20130101); F28F
9/0243 (20130101) |
Current International
Class: |
F28F
9/22 (20060101); F28F 9/02 (20060101); F28F
9/24 (20060101) |
Field of
Search: |
;165/158-161 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1584482 |
|
Oct 2010 |
|
CN |
|
105431702 |
|
Mar 2016 |
|
CN |
|
1067352 |
|
Jan 2001 |
|
EP |
|
59012294 |
|
Jan 1984 |
|
JP |
|
59044585 |
|
Mar 1984 |
|
JP |
|
Other References
Effects of sealing strips on shell-side flow . . . --Yang (Dec.
2013) (Year: 2013). cited by examiner .
Sealing Strips in Tubular Heat Exchangers--Taylor (Aug. 1987)
(Year: 1987). cited by examiner .
International Search Report issued in International Application No.
PCT/US2020/034659 dated Sep. 15, 2020 (3 pages). cited by applicant
.
Written Opinion issued in International Application No.
PCT/US2020/034659 dated Sep. 15, 2020 (11 pages). cited by
applicant .
Office Action issued in corresponding TW Application No. 109118177
dated May 3, 2021 (18 pages). cited by applicant.
|
Primary Examiner: Tran; Len
Assistant Examiner: Hopkins; Jenna M
Attorney, Agent or Firm: Seed IP Law Group LLP
Claims
What is claimed is:
1. A heat exchanger comprising: a shell having a longitudinal axis
and configured to receive a first fluid; a plurality of baffles
each mounted in the shell at a helix angle H.sub.B to guide a first
fluid flow into a helical pattern through the shell, wherein each
of the plurality of baffles comprises: an outer circumferential
edge longitudinally spaced apart from the outer circumferential
edge positions of the rest of the plurality of baffles; a proximal
radial edge spaced from a distal radial edge; a proximal side
opposite from a distal side; and a plurality of spaced apart holes
configured to be traversed by a plurality of axially extending
tubes configured to carry a second fluid; and a first plurality of
seal strips, each having a first end and a second end, radially
disposed between the shell and the plurality of axially extending
tubes and each respectively positioned between any two adjacent
baffles; wherein each of the first plurality of seal strips is
disposed to have the first end of each seal strip proximate to the
distal side of a respective baffle and the second end of each seal
strip proximate to the proximal side of a respective baffle at a
helix angle H.sub.s that is greater than 5.degree. and less than
the baffle helix angle H.sub.B, where the helix angles H.sub.B and
H.sub.s are defined as the angle of the respective baffle or seal
strip relative to the longitudinal axis of the shell, and wherein
each of the first plurality of seal strips have an angle greater
than 0.degree. up to 80.degree. formed between each of the first
plurality of seal strips and a line orthogonal to the proximal side
of the respective baffle and the distal side of the respective
baffle.
2. The heat exchanger of claim 1, wherein the seal strips, in part,
are configured in part to direct a flow of fluid helically toward
an outlet and in part to direct a flow of fluid away from the shell
and toward the plurality of axially extending tubes.
3. The heat exchanger of claim 1, wherein: the first plurality of
seal strips are disposed from a distal side of a first baffle from
adjacent to a proximal radial edge of the first baffle to a
proximal side of a second baffle adjacent to a distal radial edge
of the second baffle, wherein the first and second baffles are
located in a same sector or quadrant; or the first plurality of
seal strips are disposed from a distal side of a first baffle from
intermediate the proximal radial edge and distal radial edge of the
first baffle to a proximal side of a second baffle intermediate a
proximal radial edge and a distal radial edge of the second baffle,
wherein the second baffle is located in a different sector or
quadrant than the first baffle.
4. The heat exchanger of claim 1, wherein the first end of each of
the first plurality of seal strips is coupled to the distal side of
a first of the plurality of baffles, and wherein the second end of
each of the first plurality of seal strips is coupled to the
proximal side of a second of the plurality of baffles.
5. The heat exchanger of claim 1, wherein the plurality of baffles
are elliptical sector-shaped baffles.
6. The heat exchanger of claim 1, wherein the first plurality of
seal strips have an inner surface and an outer surface, and wherein
the first plurality of seal strips are angled from the outer
surface to the inner surface by an angle from orthogonal to the
shell in the direction defined from a proximal radial edge to a
distal radial edge of the one of the plurality of baffles.
7. The heat exchanger of claim 6, wherein each of the first
plurality of seal strips is angled by 15.degree. up to 45.degree.
from orthogonal to the shell.
8. The heat exchanger of claim 1, wherein an outer surface of each
of the first plurality of seal strips is disposed proximate to an
inner surface of the shell.
9. The heat exchanger of claim 1, wherein an inner surface of each
of the first plurality of seal strips is spaced from an outer
surface of a closest tube of the plurality of axially extending
tubes by a distance that is equal to a distance between outer
diameters of two adjacent tubes of the plurality of axially
extending tubes.
10. The heat exchanger of claim 1, wherein each of the plurality of
baffles includes at least one of the first plurality of seal strips
coupled to the proximal side and at least one of the first
plurality of seal strips coupled to the distal side.
11. The heat exchanger of claim 1, wherein each of the first
plurality of seal strips coupled to the distal side of each of the
plurality of baffles is offset rotationally about the longitudinal
axis from each of the plurality of seal strips coupled to the
proximal side of each of the plurality of baffles.
12. The heat exchanger of claim 1, wherein each of the first
plurality of seal strips have a curved outer diameter with a
curvature that is elliptical and wherein each of the first
plurality of seal strips have a curved inner diameter with a
curvature that is elliptical.
13. The heat exchanger of claim 1, wherein each of the first
plurality of seal strips has a width, outer diameter minus inner
diameter, that varies along a length, first end to second end, of
the seal strip, and wherein each of the first plurality of seal
strips has a depth, proximal side to distal side, that varies along
the width or the length of the seal strip.
14. The heat exchanger of claim 1, wherein an equal number of seal
strips are coupled to each baffle of the plurality of baffles.
15. The heat exchanger of claim 1, wherein a number of seal strips
per rotation about the longitudinal axis of the shell is a multiple
of a number of baffles per rotation about the longitudinal axis of
the shell.
16. The heat exchanger of claim 1, wherein the first plurality of
seal strips are formed of steel.
17. The heat exchanger of claim 1, further comprising: a second
plurality of seal strips, each having a first end and a second end
radially disposed between the shell and the plurality of axially
extending tubes and each respectively positioned between any two
baffles, wherein each of the second plurality of seal strips is
disposed from a proximal of the plurality of baffles to a distal of
the plurality of baffles at a helix angle H.sub.2s that is greater
than 5.degree., different than helix angle H.sub.s, and less than
the baffle helix angle H.sub.B, where the helix angles H.sub.B,
H.sub.s, H.sub.2s are defined as the angle of the respective baffle
or seal strip relative to the longitudinal axis of the shell.
18. The heat exchanger of claim 1, further comprising: a second
plurality of seal strips, each having a first end and a second end
radially disposed between the shell and the plurality of axially
extending tubes and each respectively positioned between any two
adjacent baffles, wherein each of the second plurality of seal
strips is disposed from a proximal radial edge of a baffle to a
distal radial edge of the adjacent baffles.
19. The heat exchanger of claim 18, wherein an inner surface of
each of the second plurality of seal strips is spaced from an outer
surface of a closest tube of the plurality of axially extending
tubes by a distance that is equal to a distance between outer
diameters of two adjacent tubes of the plurality of axially
extending tubes.
20. A method of assembling of a heat exchanger, the method
comprising: providing a center rod having a longitudinal axis;
mounting a plurality of elliptical sector-shaped baffles to the
center rod at an angle to the longitudinal axis of the center rod
such that a helical pattern is formed by the plurality of baffles,
wherein each of the plurality of baffles comprises: an outer
circumferential edge longitudinally spaced apart from the outer
circumferential edge positions of the rest of the plurality of
baffles; a proximal radial edge spaced from a distal radial edge; a
proximal side opposite from a distal side; and a plurality of
spaced apart holes; disposing a plurality of axially extending
tubes into the plurality of spaced apart holes of each of the
plurality of baffles, wherein the plurality of axially extending
tubes are configured to carry a second fluid; coupling a first
plurality of seal strips, each having a first end and a second end,
radially between a shell and the plurality of axially extending
tubes, wherein coupling the first plurality of seal strips
includes: coupling the first end of each of the first plurality of
seal strips to the proximal side of one of the plurality of
baffles; coupling the second end of each of the first plurality of
seal strips to the distal side of an adjacent baffle to the one of
the plurality of baffles, wherein each of the first plurality of
seal strips is disposed at a helix angle H.sub.s that is greater
than 5.degree. and less than the baffle helix angle H.sub.B, where
the helix angles H.sub.B and H.sub.s are defined as the angle of
the respective baffle or seal strip relative to the longitudinal
axis of the shell; and angling each of the first plurality of seal
strips to form an angle greater than 0.degree. up to 80.degree.
between each of the first plurality of seal strips and a line
orthogonal to the proximal side of the respective baffle and the
distal side of the respective baffle; and disposing the assembled
center rod, plurality of baffles, plurality of axially extending
tubes, and first plurality of seal strips within the shell that is
configured to receive a first fluid.
21. The method of assembly of claim 20, wherein the coupled first
plurality of seal strips have an inner surface and an outer
surface, and wherein coupling the first plurality of seal strips
further includes: angling the coupled first plurality of seal
strips from the outer surface to the inner surface by an angle from
orthogonal to the shell in the direction defined from the proximal
radial edge to the distal radial edge of the one of the plurality
of baffles.
22. The method of assembly of claim 20, wherein coupling the first
plurality of seal strips further includes: spacing an inner surface
of each of the first plurality of seal strips from an outer surface
of a closest tube of the plurality of axially extending tubes by a
distance that is equal to a distance between outer diameters of two
adjacent tubes of the plurality of axially extending tubes.
23. The method of assembly of claim 20, wherein coupling the first
plurality of seal strips further includes: rotationally offsetting
each of the first plurality of seal strips coupled to the distal
side of each of the plurality of baffles from each of the plurality
of seal strips coupled to the proximal side of each of the
plurality of baffles.
24. The method of assembly of claim 20, further comprising:
coupling a second plurality of seal strips having a first end and a
second end radially between the shell and the plurality of axially
extending tubes, wherein coupling the second plurality of seal
strips includes: coupling the first end of each of the second
plurality of seal strips to the proximal radial edge of the distal
side of one of the plurality of baffles; and coupling the second
end of each of the second plurality of seal strips to the distal
radial edge of the proximate side of another of the plurality of
baffles, wherein each of the second plurality of seal strips
extends parallel to the longitudinal axis of the shell.
25. A heat exchanger, comprising: a shell having a longitudinal
axis and configured to receive a first fluid; a plurality of
baffles mounted in the shell at an angle to the longitudinal axis,
spaced apart from each other along the longitudinal axis, and
configured to guide a flow of the first fluid along a helical
pattern through the shell, each of the baffles comprising: an outer
circumferential edge; a proximal radial edge spaced from a distal
radial edge; a proximal side opposite from a distal side; and a
plurality of spaced apart holes formed through each baffle from the
proximal side to the distal side, the holes configured to be
traversed by a plurality of axially extending tubes with the tubes
configured to carry a second fluid; and a plurality of seal
members, each comprising a first end and a second end, the seal
members radially disposed between the shell and the plurality of
axially extending tubes, and the first end of each seal member
coupled to the distal side of a respective baffle and the second
end of each seal member coupled to the proximal side of a
respective baffle, wherein each seal member is disposed at an angle
from orthogonal to the proximal side of the respective baffle, and
the angle is from greater than 0.degree. up to 80.degree. in a
direction defined from the proximal radial edge to the distal
radial edge of the respective baffle.
26. The heat exchanger of claim 25, wherein the seal members
comprise seal strips or seal rods.
27. A heat exchanger comprising: a shell having a longitudinal axis
and configured to receive a first fluid; a plurality of baffles
each mounted in the shell at a helix angle H.sub.B to guide a first
fluid flow into a helical pattern through the shell, wherein each
of the plurality of baffles comprises: an outer circumferential
edge longitudinally spaced apart from the outer circumferential
edge positions of the rest of the plurality of baffles; a proximal
radial edge spaced from a distal radial edge; a proximal side
opposite from a distal side; and a plurality of spaced apart holes
configured to be traversed by a plurality of axially extending
tubes configured to carry a second fluid; and a first plurality of
circumferentially offset seal strips, each having a first end and a
second end, radially disposed between the shell and the plurality
of axially extending tubes and each respectively positioned between
any two adjacent baffles, wherein each of the first plurality of
circumferentially offset seal strips have an angle greater than
0.degree. up to 80.degree. formed between each of the first
plurality of circumferentially offset seal strips and a line
orthogonal to the two adjacent baffles.
28. The heat exchanger of claim 27, wherein each of the plurality
of baffles is connected to at least two of the first plurality of
seal strips, including a distal seal strip connected to a distal
side of a baffle, and a proximal seal strip connected to a proximal
side of the same baffle, and wherein the proximal seal strip is
circumferentially offset from the distal seal strip.
29. The heat exchanger of claim 27, wherein each of the first
plurality of seal strips is parallel to a longitudinal axis of the
heat exchanger.
Description
BACKGROUND
Heat-exchanging assemblies target increased performance by
maximizing the ratio of heat transfer to pressure drop, whilst
providing reduced installation and maintenance costs and effective
protection against damage from vibration, or loss of efficiency due
to fouling.
Whether it is the offshore, refinery, power, petrochemical, or
paper and food industries, heat exchangers are often the core of
the above-enumerated objectives. Numerous configurations of heat
exchangers are known and used for a variety of applications. One of
the widely used configurations of heat exchangers is a shell and
tube heat exchanger, as shown in FIG. 1 by way of example. The
shell and tube heat exchanger of FIG. 1 includes a cylindrical
shell 10 that houses a bundle of parallel tubes 11, which extend
between two end plates 12. A first fluid 13 flows in and through
the space between the two end plates so as to come into contact
with the bundle of parallel tubes 11, through which a second fluid
14 passes through. To provide an improved heat exchange between the
two fluids, the flow of the first fluid 13 is defined by
intermediate baffles 15 forming respective compartments, which are
arranged so that the flow of the first fluid 13 changes its
direction in passing from one compartment to the next. The baffles
15, configured as circular segments, are installed perpendicular to
a longitudinal axis 16 of the shell 10 to provide a zigzag flow 17
of the first fluid 13.
Disadvantageously, in shell and tube heat exchangers, such as the
heat exchanger shown in FIG. 1, the second fluid has to sharply
change the direction of its flow several times along the length of
the shell. These sharp changes in flow direction cause a reduction
in the dynamic pressure of the second fluid and non-uniform flow
velocity thereof, which, in combination, adversely affect the
performance of the heat exchanger. Further, cleaning of shell and
tube heat exchangers requires that the bundle of parallel tubes 11
be removed from the shell 10 or else only clean fluids can be used
as the first fluid 13 that is flowed within the shell 10 of the
shell and tube heat exchanger. Making the bundle of parallel tubes
11 removable requires sufficient clearance between the bundle of
parallel tubes 11 and the shell 10 to allow for non-damaging
removal. Typically the gap between the bundle of parallel tubes 11
and the shell 10 is large enough that a significant amount of the
first fluid 13 to be heated or cooled will bypass the bundle of
parallel tubes 11 and mix with the first fluid 13 that has been
heated or cooled at the outlet of the shell and tube heat
exchanger.
Referring still to shell and tube heat exchangers (e.g., the heat
exchanger shown in FIG. 1), it is well known that a perpendicular
position of baffles relative to the longitudinal axis of the shell
results in a relatively inefficient heat transfer rate/pressure
drop ratio, because the baffles produce a large form drag. Adjacent
baffles extending parallel to one another and at a right angle with
respect to the longitudinal axis of the shell define a cross flow
path characterized by numerous sharp turns between adjacent
channels. The efficiency of heat transfer can be improved by
reducing the spacing between the baffles. However, decreasing the
spacing results in large recirculation zones and forces a larger
fraction of the flow to leak between the tubes and the baffle and
along the outer edges of the baffles. The non-uniformity of flow
distribution within each segment defined between the adjacent
baffles causes numerous eddies, stagnation regions, and
expansion/contraction, which decreases a local temperature
difference. A further factor contributing to a decreased heat
transfer rate is attributed to the fact that the tubes traversed by
the first fluid have to be positioned at a certain radial distance
from the shell. Accordingly, the cross flow around the peripherally
located tubes is faster than around centrally mounted tubes.
Thus, conventional baffle arrangement as described above results in
flow bypass through baffle-to-shell clearances and flow leakage
through tube-to-baffles clearances. Bypass and leakage flow reduces
the cross-flow heat transfer while the flow maldistribution caused
by significant velocity variations increases back-flow and eddies
in the dead zones, which in turn leads to the disposition of
fouling materials on the outside of the tubes of the bundle of
tubes. If the heat exchanger is left to continue operating after
disposition of fouling materials within the shell, then a
significant loss in performance will be experienced over time,
which will translate into an increase in operating cost and
consumption of energy. If the heat exchanger is removed from
service to be cleaned due to the buildup of fouling materials,
there will be a loss or reduction in production, which translates
into an operating cost similar to or higher than the value of the
heat exchanger. Further, heat exchangers that are left in a fouled
state for too long will develop hardened deposits, which will be
difficult to remove and can cause corrosion in local regions with
higher temperatures. The bundle of tubes on which the hardened
deposits develop and on which corrosion occurs may deteriorate to a
point where the bundle of tubes must be removed from service and
the damaged tubes are plugged.
Furthermore, conventional arrangement may experience flow-induced
vibration of the tubes since long tubes reaching often 24-feet long
are supported by a succession of baffles which, in order to solve
the problem associated with the non-uniform velocity, are spaced
apart at a substantial distance.
Helically baffled heat exchangers have been used to overcome the
problem of non-uniform flow in shell and tube heat exchangers. A
helical pattern of the first fluid flow may allow for a
particularly effective conversion of available pressure drop to
heat transfer and may reduce the risk of vibration of the bundle of
parallel pipes. However, the helical baffles may have large gaps
which allow the first fluid flow to leak around the baffles and may
result in both a reduced velocity across the bundle of tubes and a
lower thermal efficiency due to the loss of a temperature driving
force. These problems may particularly occur when a removable
bundle of tubes with a large tube to shell clearance is desired.
Further, bypassing of the bundle of tubes may also be particularly
severe when cooling a viscous liquid whereby the viscosity of a
liquid after it has been cooled is significantly higher than the
viscosity of the liquid when it enters the heat exchanger. In other
words, a warmer, less viscous liquid can easily flow around and
bypass the bundle of tubes compared to a cooled, more viscous
liquid.
In order to help prevent bypass of the baffles of a helically
baffled heat exchanger, sealing devices have been used. The sealing
devices for such helically baffled heat exchangers have been of
substantially the same type as the sealing devices used for the
conventional baffles and have been relatively ineffective in
preventing bypass in the helically baffled heat exchangers. In
addition, since the helically baffled heat exchangers have a
generally lower pressure drop than a segmentally baffled heat
exchanger, the penalty associated with the pressure drop induced by
the sealing devices relative to the improvement in heat transfer is
relatively high. The sealing devices used in conventional baffled
heat exchangers may provide, at best, a minor improvement in heat
transfer, and may, at worst, interfere with the helical flow path
in the bundle, thereby causing a significant reduction in heat
transfer.
SUMMARY OF INVENTION
It is desirable to configure a baffle assembly that can attain
uniformity of fluid flow without recirculation, dead zones, or
leakage/bypassing of the heat transfer surfaces. Further, it is
desirable to configure a baffle assembly with positioning of
multiple baffles and sealing devices to maintain a higher heat
transfer rate within acceptable pressure drop and vibration limits.
Additionally, a baffle assembly that allows for facilitated
maintenance of the bundle of tubes by providing a larger tube to
shell clearance to allow rapid removal and replacement for cleaning
and repair is desirable. Embodiments disclosed herein address one
or more of these.
Embodiments of the disclosure may provide a heat exchanger. The
heat exchanger may include a shell having a longitudinal axis and
configured to receive a first fluid. Further, the heat exchanger
may include a plurality of elliptical sector-shaped baffles each
mounted in the shell at an angle to the longitudinal axis to guide
a first fluid flow into a helical pattern through the shell.
Furthermore, the heat exchanger may include a first plurality of
seal strips having a first end and a second end radially disposed
between the shell and a plurality of axially extending tubes.
Additionally, each of the plurality of baffles may include an outer
circumferential edge longitudinally spaced apart from the outer
circumferential edge positions of the rest of the plurality of
baffles, a proximal radial edge spaced from a distal radial edge, a
proximal side opposite from a distal side, and a plurality of
spaced apart holes configured to be traversed by the plurality of
axially extending tubes carrying a second fluid. The first end of
each of the first plurality of seal strips may be coupled to the
distal side of one of the plurality of baffles between the proximal
radial edge and the distal radial edge of the one of the plurality
of baffles. The second end of each of the first plurality of seal
strips may be coupled to the proximal side of another of the
plurality of baffles between the proximal radial edge and the
distal radial edge of the other of the plurality of baffles.
Further, each of the first plurality of seal strips may be disposed
either orthogonal to both the distal side of the one of the
plurality of baffles and the proximal side of the other of the
plurality of baffles or at an angle from orthogonal to the proximal
side of the other of the plurality of baffles, and the angle may be
from greater than 0.degree. up to 80.degree. in a direction defined
from the proximal radial edge to the distal radial edge of the one
of the plurality of baffles.
Embodiments of the disclosure may further provide a method for
assembling a heat exchanger. The method may include providing a
center rod having a longitudinal axis. Further, the method may
include mounting a plurality of elliptical sector-shaped baffles to
the center rod at an angle to the longitudinal axis of the center
rod such that a helical pattern is formed by the plurality of
baffles. Each of the plurality of baffles may include an outer
circumferential edge longitudinally spaced apart from the outer
circumferential edge positions of the rest of the plurality of
baffles, a proximal radial edge spaced from a distal radial edge, a
proximal side opposite from a distal side, and a plurality of
spaced apart holes. Furthermore, the method may include disposing a
plurality of axially extending tubes into the plurality of spaced
apart holes of each of the plurality of baffles, and the plurality
of axially extending tubes may carry a second fluid. Moreover, the
method may include coupling a first plurality of seal strips having
a first end and a second end radially between the shell and the
plurality of axially extending tubes. Coupling the first plurality
of seal strips may include coupling the first end of each of the
first plurality of seal strips to the distal side of one of the
plurality of baffles and coupling the second end of each of the
first plurality of seal strips to the proximal side of another of
the plurality of baffles. Each of the first plurality of seal
strips may be disposed either orthogonal to both the distal side of
the one of the plurality of baffles and the proximal side of the
other of the plurality of baffles or at an angle from orthogonal to
the proximal side of the other of the plurality of baffles, and the
angle may be from greater than 0.degree. up to 80.degree. in a
direction defined from the distal radial edge to the proximal
radial edge of the one of the plurality of baffles.
In one aspect, embodiments disclosed herein relate to a heat
exchanger. The heat exchanger may include a shell, a plurality of
baffles, a plurality of axially extending tubes, and a plurality of
seal strips. The shell may have a longitudinal axis and may be
configured to receive a first fluid. A plurality of baffles, each
mounted in the shell at a helix angle H.sub.B, may be configured to
guide a flow of the first fluid into a helical pattern through the
shell. Each of the plurality of baffles may include: an outer
circumferential edge longitudinally spaced apart from the outer
circumferential edge positions of the rest of the plurality of
baffles; a proximal radial edge spaced from a distal radial edge; a
proximal side opposite from a distal side; and a plurality of
spaced apart holes configured to be traversed by a plurality of the
axially extending tubes configured to carry a second fluid. The
plurality of seal strips each have a first end and a second end,
radially disposed between the shell and the plurality of axially
extending tubes and each are respectively positioned between any
two longitudinally adjacent baffles, wherein each of the first
plurality of seal strips is disposed from a proximal of the
plurality of baffles to a distal of the plurality of baffles at a
helix angle H.sub.s that is greater than 5.degree. and less than
the baffle helix angle H.sub.B, where the helix angles H.sub.B and
H.sub.s are defined as the angle of the respective baffle or seal
strip relative to the longitudinal axis of the shell.
In some embodiments, the seal strips, in part, may be configured to
direct a flow of fluid helically toward the outlet. The first
plurality of seal strips may be disposed from a distal side of a
first baffle from adjacent to a proximal radial edge of the first
baffle to a proximal side of a second baffle adjacent to a distal
radial edge of the second baffle, wherein the first and second
baffles are located in a same sector or quadrant. Alternatively,
the first plurality of seal strips may be disposed from a distal
side of a first baffle from intermediate the proximal radial edge
and distal radial edge of the first baffle to a proximal side of a
second baffle intermediate a proximal radial edge and a distal
radial edge of the second baffle, wherein the second baffle is
located in a different sector or quadrant than the first
baffle.
The first end of each of the first plurality of seal strips may, in
some embodiments, be coupled to the distal side of a first of the
plurality of baffles, and the second end of each of the first
plurality of seal strips may be coupled to the proximal side of a
second of the plurality of baffles.
The first plurality of seal strips may each have an inner surface
and an outer surface. The first plurality of seal strips may be
angled from the outer surface to the inner surface by an angle from
orthogonal to the shell in the direction defined from a proximal
radial edge to a distal radial edge of the one of the plurality of
baffles.
In some embodiments, each of the first plurality of seal strips may
be angled by 15.degree. up to 45.degree. from orthogonal to the
shell such that the first fluid flow hits the seal strip at a
105.degree. up to 135.degree. angle.
An outer surface of each of the first plurality of seal strips may
be disposed substantially proximate to an inner surface of the
shell. An inner surface of each of the first plurality of seal
strips, in some embodiments, may be spaced from an outer diameter
of a closest tube of the plurality of axially extending tubes by a
distance that is equal to a distance between outer diameters of two
adjacent tubes of the plurality of axially extending tubes.
Each of the plurality of baffles may include at least one of the
first plurality of seal strips coupled to the proximal side and at
least one of the first plurality of seal strips coupled to the
distal side of the baffle. In some embodiments, each of the first
plurality of seal strips coupled to the distal side of each of the
plurality of baffles may be offset rotationally about the
longitudinal axis from each of the plurality of seal strips coupled
to the proximal side of each of the plurality of baffles.
In some embodiments, each of the first plurality of seal strips
have a curved outer diameter with a curvature that is elliptical
and/or wherein each of the first plurality of seal strips have a
curved inner diameter with a curvature that is elliptical.
Each of the first plurality of seal strips may have a width, outer
diameter minus inner diameter, that varies along a length, first
end to second end, of the seal strip, and/or wherein each of the
first plurality of seal strips has a depth, proximal side to distal
side, that varies along the width or the length of the seal
strip.
In some embodiments, an equal number of seal strips may be coupled
to each baffle of the plurality of baffles. In some embodiments, a
number of seal strips per rotation about the longitudinal axis of
the shell is a multiple of a number of baffles per rotation about
the longitudinal axis of the shell.
Heat exchangers according to embodiments herein may further include
a second plurality of seal strips, each having a first end and a
second end radially disposed between the shell and the plurality of
axially extending tubes and each respectively positioned between
any two baffles. Each of the second plurality of seal strips may be
disposed from a proximal of the plurality of baffles to a distal of
the plurality of baffles at a helix angle H.sub.2s that is greater
than 5.degree., different than helix angle H.sub.s, and less than
the baffle helix angle H.sub.B, where the helix angles H.sub.B,
H.sub.s, H.sub.2s are defined as the angle of the respective baffle
or seal strip relative to the longitudinal axis of the shell.
Heat exchangers according to embodiments herein may include a
second plurality of seal strips. Each may have a first end and a
second end radially disposed between the shell and the plurality of
axially extending tubes and each respectively may be positioned
between any two adjacent baffles, where each of the second
plurality of seal strips is disposed from a proximal radial edge of
a baffle to a distal radial edge of the adjacent baffles. In some
embodiments, an inner diameter of each of the second plurality of
seal strips may be spaced from an outer diameter of a closest tube
of the plurality of axially extending tubes by a distance that is
equal to a distance between outer diameters of two adjacent tubes
of the plurality of axially extending tubes.
In another aspect, embodiments herein relate to a method of
assembling a heat exchanger. The method may including: providing a
center rod having a longitudinal axis, and mounting a plurality of
elliptical sector-shaped baffles to the center rod at an angle to
the longitudinal axis of the center rod such that a helical pattern
is formed by the plurality of baffles. Each of the plurality of
baffles may include: an outer circumferential edge longitudinally
spaced apart from the outer circumferential edge positions of the
rest of the plurality of baffles; a proximal radial edge spaced
from a distal radial edge; a proximal side opposite from a distal
side; and a plurality of spaced apart holes; disposing a plurality
of axially extending tubes into the plurality of spaced apart holes
of each of the plurality of baffles, wherein the plurality of
axially extending tubes are configured to carry a second fluid. The
method may further include coupling a first plurality of seal
strips, each having a first end and a second end, radially between
the shell and the plurality of axially extending tubes. Coupling
the first plurality of seal strips may include: coupling the first
end of each of the first plurality of seal strips to a proximal of
one of the plurality of baffles; and coupling the second end of
each of the first plurality of seal strips to another, more distal,
of the plurality of baffles. Each of the first plurality of seal
strips may be disposed from the proximal of the plurality of
baffles to the distal of the plurality of baffles at a helix angle
H.sub.s that is greater than 5.degree. and less than the baffle
helix angle H.sub.B, where the helix angles H.sub.B and H.sub.s are
defined as the angle of the respective baffle or seal strip
relative to the longitudinal axis of the shell. The method may
further include disposing the assembled center rod, plurality of
baffles, plurality of axially extending tubes, and first plurality
of seal strips within a shell that is configured to receive a first
fluid.
The coupled first plurality of seal strips may each have an inner
diameter and an outer diameter. In some embodiments, coupling the
first plurality of seal strips may further include: angling the
coupled first plurality of seal strips from the outer diameter to
the inner diameter by an angle from orthogonal to the shell in the
direction defined from the proximal radial edge to the distal
radial edge of the one of the plurality of baffles. In some
embodiments, coupling the first plurality of seal strips may
further include: spacing an inner diameter of each of the first
plurality of seal strips from an outer diameter of a closest tube
of the plurality of axially extending tubes by a distance that is
equal to a distance between outer diameters of two adjacent tubes
of the plurality of axially extending tubes. And, in some
embodiments, coupling the first plurality of seal strips may
further include rotationally offsetting each of the first plurality
of seal strips coupled to the distal side of each of the plurality
of baffles from each of the plurality of seal strips coupled to the
proximal side of each of the plurality of baffles.
The method of assembly may further include coupling a second
plurality of seal strips having a first end and a second end
radially between the shell and the plurality of axially extending
tubes. Coupling the second plurality of seal strips may include:
coupling the first end of each of the second plurality of seal
strips to the proximal radial edge of the distal side of one of the
plurality of baffles; and coupling the second end of each of the
second plurality of seal strips to the distal radial edge of the
proximate side of another of the plurality of baffles, wherein each
of the second plurality of seal strips extends parallel to the
longitudinal axis of the shell.
In another aspect, embodiments herein are directed toward a heat
exchanger. The heat exchanger may include: a shell having a
longitudinal axis and configured to receive a first fluid; a
plurality of baffles mounted in the shell at an angle to the
longitudinal axis, spaced apart from each other along the
longitudinal axis, and configured to guide a flow of the first
fluid along a helical pattern through the shell, each of the
baffles comprising: an outer circumferential edge; a proximal
radial edge spaced from a distal radial edge; a proximal side
opposite from a distal side; and a plurality of spaced apart holes
formed through each baffle from the proximal side to the distal
side, the holes configured to be traversed by a plurality of
axially extending tubes with the tubes configured to carry a second
fluid; and a plurality of seal members, each comprising a first end
and a second end, the seal members radially disposed between the
shell and the plurality of axially extending tubes, and the first
end of each seal member coupled to the distal side of a respective
baffle and the second end of each seal member coupled to the
proximal side of a respective baffle. In some embodiments, the seal
members may include seal strips or seal rods.
In another aspect, embodiments herein are directed toward a heat
exchanger including a shell having a longitudinal axis, the shell
being configured to receive a first fluid. A plurality of baffles
are each mounted in the shell at a helix angle H.sub.B to guide a
first fluid flow into a helical pattern through the shell. Each of
the plurality of baffles may include: an outer circumferential edge
longitudinally spaced apart from the outer circumferential edge
positions of the rest of the plurality of baffles; a proximal
radial edge spaced from a distal radial edge; a proximal side
opposite from a distal side; and a plurality of spaced apart holes
configured to be traversed by a plurality of axially extending
tubes configured to carry a second fluid. A first plurality of
circumferentially offset seal strips, each having a first end and a
second end, may be radially disposed between the shell and the
plurality of axially extending tubes and each may be respectively
positioned between any two adjacent baffles. In some embodiments,
each of the plurality of baffles is connected to at least two of
the first plurality of seal strips, including a distal seal strip
connected to a distal side of a baffle, and a proximal seal strip
connected to a proximal side of the same baffle, and wherein the
proximal seal strip is circumferentially offset from the distal
seal strip. Each of the first plurality of seal strips may be
parallel to a longitudinal axis of the heat exchanger in some
embodiments.
Other aspects and advantages of the invention will be apparent from
the following description and the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 illustrates a diagrammatic view of flow distribution in a
conventional shell and tube heat exchanger.
FIG. 2 illustrates a diagrammatic perspective view of a heat
exchanger according to one or more embodiments of the present
disclosure.
FIG. 3 illustrates a perspective view of a baffle cage of a heat
exchanger according to one or more embodiments of the present
disclosure.
FIGS. 4A and 4B illustrate a perspective view of baffles of a heat
exchanger according to one or more embodiments of the present
disclosure.
FIGS. 5A-5E illustrate multiple views of a heat exchanger according
to one or more embodiments of the present disclosure.
FIGS. 6A-6D illustrate perspective views of heat exchangers
according to multiple embodiments of the present disclosure.
FIG. 7 illustrates a side view of a heat exchanger according to one
or more embodiments of the present disclosure.
FIG. 8 illustrates a side view of a heat exchanger according to one
or more embodiments of the present disclosure.
FIG. 9 illustrates a side view of a heat exchanger according to one
or more embodiments of the present disclosure.
FIG. 10 is a graphical representation of data comparing a heat
exchanger according to embodiments herein with prior art heat
exchangers.
DETAILED DESCRIPTION
Embodiments of the present disclosure are described below in detail
with reference to the accompanying figures. Like elements in the
various figures may be denoted by like reference numerals for
consistency. Further, in the following detailed description,
numerous specific details are set forth in order to provide a more
thorough understanding of the claimed subject matter. However, it
will be apparent to one having ordinary skill in the art that the
embodiments described may be practiced without these specific
details. In other instances, well-known features have not been
described in detail to avoid unnecessarily complicating the
description.
Referring to FIG. 2, in one or more embodiments, a
helically-baffled heat exchanger 200 according to one or more
embodiments of the present disclosure is shown. The heat exchanger
200 may include a shell 220 through which a first fluid is passed,
a plurality of axially extending tubes 230 through which a second
fluid is passed, and a plurality of elliptical sector-shaped
baffles 240. By "elliptical sector-shaped," it should be understood
that the baffles take the general form of an elliptical sector,
which geometrically includes a region bounded by an arc and line
segments connecting the center of the ellipse (the origin) and the
endpoints of the arc, but may not be inclusive of the entire sector
so as to account for other components of the heat exchanger (tubes,
etc.) and the manner of installation of the baffle (e.g.,
encompassing or abutting a central tube, or accommodating tubes
along the periphery of the elliptical sector, as illustrated in
FIGS. 3 and 4, for example).
The shell 220 may include an inlet 228 and an outlet 229 between
which the first fluid may pass within the shell 220. Each of the
baffles 240 may be positioned at an angle .lamda. relative to a
line (N-N) that is normal to a longitudinal axis 221 of the shell
220 in order to guide a first fluid flow 222 into a helical pattern
231 across the shell 220 from the inlet 228 to the outlet 229. The
helical pattern 231 of the first fluid flow 222 may allow for an
effective conversion of available pressure drop to heat transfer
and reduced risk of vibration due to the fact that the unsupported
tube length is minimized. In one or more embodiments, there may be
no dead spots for fouling along the first fluid flow 222, and the
amount of heat transfer may be increased due to elimination of
eddies or back mixing. Further, in one or more embodiments, a
direction of the first fluid flow 222 may be opposite to a
direction of a second fluid flow 232 within the tubes 230. In other
words, in one or more embodiments, the second fluid may flow in a
direction that is substantially from the outlet 229 to the inlet
228. Additionally, although the baffles 240, as shown in FIG. 2,
are flat, in one or more embodiments, opposite sides of each baffle
may be curved to guide the first fluid flow 222 along the helical
pattern.
Referring now to FIG. 3, a baffle cage 341 according to one or more
embodiments of the present disclosure is shown. The baffle cage 341
may include successive baffles 340 positioned at an angle from
normal to a longitudinal axis (not shown) of the baffle cage 341,
and the successive baffles 340 may be rotationally and
longitudinally offset from each other such that a helical pattern
is formed. The rotational offset between successive baffles 340 may
be such that at least a proximal radial edge 344 of one baffle 340
overlaps or abuts a distal radial edge 345 of an adjacent baffle
340 in a longitudinal direction. For example, FIG. 3 illustrates an
embodiment in which a proximal radial edge 344 of each baffle 340
overlaps a distal edge 345 of the successive baffle 340. In one or
more embodiments, a proximal radial edge 344 of each baffle 340 may
be the radial edge of the baffle 340 that is axially closest to an
inlet (not shown) of a shell (not shown) of a heat exchanger, and a
distal radial edge 345 of each baffle 340 may be the radial edge of
the baffle 340 that is axially farthest from the inlet of the shell
of the heat exchanger. Further, in one or more embodiments, there
may be an equal number of baffles 340 per 360.degree. rotation
about the longitudinal axis about which the baffles 340 are
disposed. Furthermore, the baffles 340 may support multiple tubes
330 and may guide a first fluid flow (not shown) in a helical path.
Additionally, in one or more embodiments, the baffles 340 may be
interconnected by a plurality of rods 342. A spacer 349 may
optionally be used during construction to ensure baffle spacing. As
illustrated, spacer 349 is rectangular, although other shapes may
be used. Still referring to FIG. 3, in one or more embodiments,
each of the baffles 340 may have an outer circumferential edge 343,
and each outer circumferential edge 343 may be spaced apart from
the outer circumferential edge 343 of an adjacent baffle 340. Each
of the baffles may also include a proximal radial edge 344 at one
end of the outer circumferential edge 343 and a distal radial edge
345 at the other end of the outer circumferential edge 343 such
that the elliptical sector-shaped baffles 340 are defined by the
outer circumferential edge 343, the proximal radial edge 344, and
the distal radial edge 345. Furthermore, each of the baffles may
have a proximal side 346 and a distal side 347 that are opposite of
each other as well as a plurality of spaced apart holes 348 that
extend through the baffles 340 from the proximal side 346 to the
distal side 347. In one or more embodiments, a proximal side 346 of
each baffle 340 may be the side of the baffle 340 that is axially
closest to the inlet of the shell of the heat exchanger, and a
distal side 347 may be the side of each baffle 340 that is axially
farthest from the inlet of the shell of the heat exchanger. One
tube 330 of the plurality of axially extending tubes 330 may pass
through each of the holes 348 in the baffles 340. In one or more
embodiments, the holes 348 of one baffle 340 may align with holes
on another baffle 340 such that the axially extending tubes 330 may
fit through holes 348 and may be supported by multiple baffles 340.
It is noted that, while not illustrated on all baffles 340, each of
the baffles 340 may contain through holes 348.
As illustrated in FIG. 3, the tubes 330 and through holes 348 do
not extend all the way to circumferential edge 343. Thus, when
installed within a shell (not shown), a gap would be present
between the shell and the outermost tubes 330. A tube cage 341,
according to embodiments herein, may include a plurality of seal
rods or seal strips 350 disposed at an angle such that the fluid
flowing through the shell is, at least in part, directed back
towards the tubes 330. Strips 350 may thus provide a dual function
of enhanced sealing and structural support, decreasing the amount
of fluid that may bypass the plurality of tubes as well as
supporting the structure of the cage 341.
In addition to the sealing and structural support function of the
strips 350, which may be referred to herein as seal strips, the
strips 350 may be positioned in a manner so as to provide the
sealing function with a low pressure drop, providing a flow barrier
to prevent fluid flowing in the gap between the tubes 330 and the
baffle edge 343 through the entirety of the helical flow path. The
flow barrier function could alternatively be obtained by use of
other structures, such as longitudinal strips having a
substantially rectangular shape disposed such that the space
between the tube bundle and the shell is effectively blocked;
however such a flow barrier would come at the at the expense of a
significant pressure drop. In contrast to longitudinal strips,
embodiments herein are directed toward strips that are designed and
oriented to provide enhanced sealing, structural support, and a
relatively low pressure drop, as will be described more fully
below.
Rods 342, as described above, are optional and may be used to
additionally serve the purpose of supporting baffles during tube
insertion. Thus, although rods are shown to interconnect the
baffles in FIG. 3, in one or more embodiments of the present
disclosure, rods are not necessary to support and interconnect the
baffles 340. Instead, as shown and described in further detail
below, in one or more embodiments, strips may be used to support
and interconnect the baffles about a center rod.
Referring now to FIGS. 4A and 4B, baffles 440 according to one or
more embodiments of the present disclosure are shown. In one or
more embodiments, a plurality of baffles 440 may be coupled to a
center rod 423 within a shell (not shown) of a heat exchanger (not
shown). Successive baffles 440 may be positioned at an angle from
normal to a longitudinal axis 424 of the center rod 423, and the
successive baffles 440 may be rotationally and longitudinally
offset from each other such that a helical pattern is formed. The
rotational offset between successive baffles 440 may be such that
at least a proximal radial edge 444 of one baffle 440 overlaps a
distal radial edge 445 of an adjacent baffle 440 in a longitudinal
direction. In one or more embodiments, a proximal radial edge 444
of each baffle 440 may be the radial edge of the baffle 440 that is
axially closest to an inlet (not shown) of a shell (not shown) of a
heat exchanger, and a distal radial edge 445 of each baffle 440 may
be the radial edge of the baffle 440 that is axially farthest from
the inlet of the shell of the heat exchanger.
Still referring to FIGS. 4A and 4B, in one or more embodiments, the
baffles 440 may be elliptical sector-shaped. Each of the baffles
440 may have an outer circumferential edge 443, and each outer
circumferential edge 443 may be spaced apart from the outer
circumferential edge 443 of an adjacent baffle 440. Each of the
baffles may also include a proximal radial edge 444 at one end of
the outer circumferential edge 443 and a distal radial edge 445 at
the other end of the outer circumferential edge 443 such that the
elliptical sector-shaped baffles 440 are defined by the outer
circumferential edge 443, the proximal radial edge 444, and the
distal radial edge 445. Furthermore, each of the baffles may have a
proximal side 446 and a distal side 447 that are opposite of each
other as well as a plurality of spaced apart holes 448 that extend
through the baffles 440 from the first side 446 to the second side
447. In one or more embodiments, a proximal side 446 of each baffle
440 may be the side of the baffle 440 that is closest to the inlet
of the shell of the heat exchanger, and a distal side 447 may be
the side of each baffle 440 that is farthest from the inlet of the
shell of the heat exchanger. One tube of a plurality of axially
extending tubes (not shown) may pass through hole 448 in the
baffles 440. In one or more embodiments, the holes 448 of one
baffle 440 may align with holes on another baffle (not shown) such
that the axially extending tubes may be supported by multiple
baffles. Additionally, in one or more embodiments, each of the
baffles 440 may include a center hole 449 at an intersection
between the proximal radial edge 444 and the distal radial edge 445
through which the center rod 423 may pass in order to couple each
of the baffles 440 to the center rod 423. While only a few holes
448 are illustrated in FIGS. 4A/B, one skilled in the art will
understand that each baffle includes multiple holes, similar to
those illustrated in FIG. 3 or 5B, for example.
The center hole 449 of each baffle 440 may be uniquely angled such
that the baffles 440 are positioned at an angle from normal to a
longitudinal axis 424 of the center rod 423. Further, in some
embodiments the baffle angle may vary along the length of the heat
exchanger, such as where proximal baffles are disposed at a first
angle to the longitudinal axis and more distal baffles are disposed
at a different angle to the longitudinal axis. As another example,
proximal baffles may be disposed at a first angle to the
longitudinal axis and more distal baffles may be successively
disposed at increasing or decreasing angles to the longitudinal
axis.
Referring now to FIGS. 5A-5E, multiple views of a heat exchanger
500 according to one or more embodiments of the present disclosure
are shown. In one or more embodiments, a heat exchanger 500 may
include a shell 520 (FIG. 5B) through which a first fluid is
passed, a plurality of axially extending tubes 530 through which a
second fluid is passed, a plurality of elliptical sector-shaped
baffles 540, and a first plurality of seal strips 550 disposed
between the baffles 540. The shell 520 may include an inlet (not
shown) and an outlet (not shown) between which the first fluid may
pass within the shell 520. Further, the plurality of tubes 530, the
plurality of baffles 540, and the first plurality of seal strips
550 may be disposed within the shell 520.
Referring to FIGS. 5A and 5B, in one or more embodiments, the
plurality of baffles 540 may be disposed such that successive
baffles 540 are positioned at an angle from a line that is normal
to a longitudinal axis 521 of the shell 520. In one or more
embodiments, the baffles 540 may be coupled to and disposed around
a center rod 523, and the successive baffles 540 may be
rotationally and longitudinally offset from each other such that a
helical pattern is formed. The rotational offset between successive
baffles 540 may be such that at least a proximal radial edge 544 of
one baffle 540 abuts or overlaps a distal radial edge 545 of an
adjacent baffle 540 in a longitudinal direction. In one or more
embodiments, a proximal radial edge 544 of each baffle 540 may be
the radial edge of the baffle 540 that is axially closest to the
inlet of the shell 520 of the heat exchanger 500, and a distal
radial edge 545 of each baffle 540 may be the radial edge of the
baffle 540 that is axially farthest from the inlet of the shell 520
of the heat exchanger 500. Further, in one or more embodiments,
there may be an equal number of baffles 540 per 360.degree.
rotation about the longitudinal axis 521 about which the baffles
540 are disposed. For example, in one or more embodiments, there
may be four baffles 540 per 360.degree. rotation about the
longitudinal axis 521 of the shell 520. While four elliptical
sector-shaped baffles per 360.degree. rotation about the
longitudinal axis of the shell are shown, in one or more
embodiments, any number of baffles of varying shapes per
360.degree. rotation about the longitudinal axis of the shell may
be utilized as long as the baffles are longitudinally and
rotationally offset such that a helical flow path is formed.
Still referring to FIGS. 5A and 5B, in one or more embodiments, the
baffles 540 may be elliptical sector-shaped. Each of the baffles
540 may have an outer circumferential edge 543, and each outer
circumferential edge 543 may be spaced apart from the outer
circumferential edge 543 of an adjacent baffle 540. Each of the
baffles 540 may also include a proximal radial edge 544 at one end
of the outer circumferential edge 543 and a distal radial edge 545
at the other end of the outer circumferential edge 543 such that
the elliptical sector-shaped baffles 540 are defined by the outer
circumferential edge 543, the proximal radial edge 544, and the
distal radial edge 545. Furthermore, each of the baffles 540 may
have a proximal side 546 and a distal side 547 that are opposite of
each other as well as a plurality of spaced apart holes 548 that
extend through the baffles 540 from the proximal side 546 to the
distal side 547. In one or more embodiments, a proximal side 546 of
each baffle 540 may be the side of the baffle 540 that is axially
closest to the inlet of the shell 520 of the heat exchanger 500,
and a distal side 547 may be the side of each baffle 540 that is
axially farthest from the inlet of the shell 520 of the heat
exchanger 500.
In one or more embodiments, one tube 530 of the plurality of
axially extending tubes 530 may pass through holes 548 in the
baffles 540, and a direction of a second fluid flow within the
tubes 530 may be opposite to a direction of a first fluid flow from
the inlet of the shell to the outlet of the shell. Further, in one
or more embodiments, the holes 548 of one baffle 540 may align with
holes on another baffle 540 such that the tubes 530 may extend
axially along an entire length of a heat exchanger 500 and such
that each of the tubes 530 be supported by multiple baffles 540.
Furthermore, a distance 534 between outer diameters 535 of each of
the tubes 530 that are disposed in each of the holes 548 may be
consistent across the entirety of the plurality of tubes 530.
Additionally, as discussed above, in one or more embodiments, each
of the baffles 540 may include a center hole 549 at an intersection
between the first radial edge 544 and the second radial edge 545
through which the center rod 523 may pass in order to couple each
of the baffles 540 to the center rod 523. The center hole 549 of
each baffle 540 may be uniquely angled such that the baffles 540
are positioned at an angle from the line normal to the longitudinal
axis 521 of the shell 520.
Further, referring to FIGS. 5A-5E, in one or more embodiments, a
first plurality of seal strips 550 may each be disposed between a
first baffle 540 and a corresponding, successive baffle 540 that is
at least a full 360.degree. rotation from the first baffle 540.
Further, each of the first plurality of seal strips 550 may be
disposed radially between the plurality of tubes 530 and an inner
surface 525 of the shell 520. In one or more embodiments, the inner
surface 525 may have a diameter 590. Further, in one or more
embodiments, each of the first plurality of seal strips 550 may be
coupled to each of the first baffle 540 and the corresponding,
successive baffle 540. In one or more embodiments, the first
plurality of seal strips 550 may be disposed such that each of the
first plurality of seal strips 550 are substantially orthogonal to
the helical path defined by the baffles within the shell 520 of the
heat exchanger 500. Referring to FIGS. 5A, 5D, and 5E, in one or
more embodiments, a first end 551 of each of the first plurality of
seal strips 550 may be coupled to the distal side 547 of one of the
plurality of baffles 540 between the proximal radial edge 544 and
the distal radial edge 545, and a second end 552 of each of the
first plurality of seal strips 550 may be coupled to the proximal
side 546 of another of the plurality of baffles 540 between the
proximal radial edge 544 and the distal radial edge 545.
As shown in FIGS. 5A and 5D, in one or more embodiments, each of
the first plurality of seal strips 550 may be disposed orthogonal
to both the distal side 547 of one baffle 540 and the proximal side
546 of another baffle 540. As shown in FIG. 5E, in other
embodiments, each of the plurality of seal strips 550 may be
connected between two baffles 540. As illustrated in FIG. 5E, the
seal strip 550 may be disposed such that an angle 595 is formed
between the seal strip 550 and a line orthogonal to the proximal
side 546 of one baffle 540 and the distal side of the other baffle
540. In some embodiments, the angle 595 may be from greater than
0.degree. up to 80.degree.. In further embodiments, the angle 595
may be one of from greater than 0.degree. up to 30.degree., from
15.degree. up to 45.degree., from 45.degree. up to 80.degree., or
from 15.degree. up to 30.degree.. Due to the possible leakage of a
first fluid between consecutive baffles of the plurality of baffles
540, the direction 522 of the first fluid flow may vary slightly
from the helical path formed by the plurality of baffles 540.
Further, due to this possible variance in the first fluid flow
direction, the angle 595 of the seal strips 550 may vary such that
each of the first plurality of seal strips 550 may be orthogonal to
the helical first fluid flow direction 522.
As shown in FIGS. 5A and 5B, the baffles 540 may be disposed in
four quadrants. In some embodiments, a seal strip 550 may connect a
first baffle 540 to a second baffle 540 in the same quadrant (or
the same sector where other than four baffles are used per
360.degree. rotation). The seal strip may be connected from the
distal side 547 of the first baffle 540 to a proximal side 546 of
the second baffle 540, at a point adjacent to the distal edge 545
of the second baffle 540, as described above. For example, the seal
strip may connect the distal side 547 of a first baffle 540 from
adjacent to the proximal edge 544 of the first baffle to the
proximal side 546 of a second baffle adjacent to the distal edge
545 of the second baffle. As another example, the seal strip may
connect the distal side 547 of a first baffle 540 from adjacent to
the proximal edge 544 of the first baffle to the proximal side 546
of a second baffle adjacent to the proximal edge 544 of the second
baffle.
In some embodiments, a seal strip 550 may connect a first baffle
540 to a second baffle 540 in an adjacent quadrant (sector). The
seal strip may be connected from the distal side 547 of the first
baffle 540 to a proximal side 546 of the second baffle 540, as
described above. For example, in some embodiments, the seal strip
may connect the distal side 547 of a first baffle 540 from
intermediate the proximal edge 544 and distal edge 545 of the first
baffle to the proximal side 546 of a second baffle intermediate the
proximal edge 544 and distal edge 545 of the second baffle.
In other embodiments, a heat exchanger may include some seal strips
550 that connect between baffles 540 in the same quadrant, while
other seal strips 550 may connect between baffles 540 in adjacent
quadrants.
In some embodiments, as shown in FIG. 5E, improved heat exchange
and reduced pressure drop may be realized where the seal strips
may, in part, direct flow helically toward the outlet. In other
words, the seal strips 550 may be disposed at a helix angle H.sub.s
less than a helix angle H.sub.B of the baffles 540, where the helix
angle is defined as the angle of the baffle or seal strip relative
to the longitudinal axis of the heat exchanger. In some
embodiments, seal strip helix angle H.sub.s may be in the range
from greater than 0.degree. to 80.degree., such as from a lower
limit of 5.degree., 10.degree., 15.degree., 20.degree., 25.degree.,
30.degree., 35.degree., 40.degree., or 45.degree. to an upper limit
of 25.degree., 30.degree., 40.degree., 45.degree., 50.degree.,
60.degree., 70.degree., 75.degree., or 80.degree., where any lower
limit may be combined with any greater upper limit according to
embodiments herein. It has been found that in some embodiments,
strips that have a helix angle H.sub.s greater than a helix angle
H.sub.B of the baffle, while providing better sealing, may disrupt
the helical flow path of the fluid (i.e., trying to drive flow back
toward the inlet). In contrast, where the seal strips encourage the
helical flow, adequate sealing is provided while both reducing
pressure drop (relative to a conventional seal) and improving heat
transfer results. In various embodiments the baffle angle H.sub.B
may be consistent or may vary along the length of the heat
exchanger. When varying baffle angles are used, for example,
proximal baffles may be disposed at a first angle (H.sub.B1, not
shown) to the longitudinal axis and more distal baffles may be
disposed at a second different angle (H.sub.B2, not shown) to the
longitudinal axis. As another example, proximal baffles may be
disposed at a first angle to the longitudinal axis and more distal
baffles may be successively disposed at increasing or decreasing
angles to the longitudinal axis (H.sub.B1<H.sub.B2<H.sub.B3
etc.).
As described above, in one or more embodiments, the first plurality
of seal strips 550 may be disposed such that each of the first
plurality of seal strips 550 are orthogonal or substantially
orthogonal to the helical path defined by the baffles within the
shell 520 of the heat exchanger 500. In other embodiments, due to
leakage and the possible variance in the first fluid flow
direction, the angle 595 of the seal strips 550 may vary such that
each of the first plurality of seal strips 550 may be orthogonal to
the helical first fluid flow direction. While it is desirable for
the fluid to flow as close to the geometric lead as possible, it is
recognized herein that this is not always the case. Hence the fluid
flow path may not be orthogonal to the seal strip 550 as shown.
Leakage and the amount of change in the first fluid flow direction
may also vary depending upon the properties of the fluid being
conveyed and the shell and baffle dimensions. Embodiments herein
may thus include estimating a first fluid flow direction, such as
by computational fluid dynamics or other simulations or
experimental investigations, such that the angle of the strip 550
may be installed accounting for the expected difference between the
geometric helical lead and the actual fluid path such that the
strip is orthogonal to the flow.
While embodiments shown in FIGS. 5A-5E may include a plurality of
seal strips that are all disposed at the same angle between one
baffle and another baffle, in one or more embodiments, the seal
strips may be disposed at different angles within the heat
exchanger. In other words, in one or more embodiments, one seal
strip of the plurality of seal strips may be disposed orthogonal to
both the distal side of one baffle and the proximal side of another
baffle, and another seal strip of the plurality of seal strips may
be disposed at an angle from orthogonal to the proximal side of one
baffle and the distal side of the other baffle, in which the angle
may be from greater than 0.degree. up to 80.degree.. Thus, while in
one or more embodiments all of the seal strips may be disposed with
the same angular disposition between baffles, in other embodiments,
a combination of seal strips of different angular dispositions may
be used. Further, while in one or more embodiments seal strips of a
first angular disposition may be used between the baffles of the
first several rotations about the longitudinal axis and seal strips
of a second angular disposition may be used between the baffles of
the remaining rotations about the longitudinal axis, in other
embodiments, different patterns of seal strips of a first angular
disposition and seal strips of a second angular disposition may be
used. Furthermore, in one or more embodiments, seal strips of more
than two angular dispositions may be used throughout the heat
exchanger in different patterns.
Further, referring to FIGS. 5B and 5C, in one or more embodiments,
each of the first plurality of seal strips may have a curved inner
surface 553 and a curved outer surface 554. In one or more
embodiments, the curved outer surface 554 of each seal strip 550
may be disposed substantially proximate the inner surface 525 of
the shell 520. Further, in one or more embodiments, the curved
outer surface 554 of one or more of the seal strips 550 may have a
clearance of 1-5 mm from the inner surface 525 of the shell 520.
For example, the curved outer surface 554 of one or more of the
seal strips 550 may have a clearance of 3 mm from the inner surface
525 of the shell 520. Additionally, a curvature of the curved outer
surface 554 of the seal strips 550 may be elliptical in shape and
may match a curvature of the inner surface 525 of the shell 520.
While noting that the seal strips may be elliptical, the appearance
of the seal strips may vary with angle. For example, where H.sub.S
is small, the strips may be nearly straight. In contrast, where
H.sub.S is large, the strips will be elliptical. The elliptical
shape ensures that each of the space between the shell and the
strip and the space between the tube bundle and the strip may be
the same along the length of the strip. Further, as the strips are
elliptical, the strips may be represented by a minor diameter and a
major diameter (not shown), where the shell diameter, spacing from
the shell diameter, and the strip angle H.sub.S may define the
elliptical nature of the strip.
Furthermore, in one or more embodiments, a curvature of the curved
inner surface 553 of each of the first plurality of seal strips 550
may be elliptical in shape and the curvature of the inner surface
553 may be different than the curvature of the outer surface 554 of
each of the first plurality of seal strips 550. In other words, in
one or more embodiments, the curvature of the inner surface 553 of
each seal strip 550 may match a curvature of an imaginary cylinder
with a diameter equal to the diameter 590 of the inner surface 525
of the shell 520 minus a radial width of the seal strip 550.
Further, the inner surface 553 of each of the first plurality of
seal strips 550 may be spaced from the outer diameter 535 of a
closest tube 530 of the plurality of axially extending tubes 530 by
a distance 557. The distance 557 between the inner surface 553 of
the seal strips 550 and the outer diameter 535 of the closest tube
530 may be equal to the distance 534 between the outer diameters
535 of two adjacent tubes 530. Furthermore, the first plurality of
seal strips 550 may be angled from the outer surface 554 to the
inner surface 553 by an angle 556 from a line 555 orthogonal to the
shell 520 in a direction of the first fluid flow 522. For example,
in one or more embodiments, each of the first plurality of seal
strips 550, which are disposed perpendicularly to the angled
baffles 540, may be angled by 15.degree.-45.degree. from a line 555
that is orthogonal to the shell 520 such that the first fluid flow
522 contacts the seal strip at a 105.degree.-135.degree. angle and
deflects back towards the plurality of tubes 530. Further, the
first plurality of seal strips 550 may have a thickness 558, and a
larger thickness 558 may be used for a heat exchanger 500 with a
larger diameter 590 of the inner surface 525 of the shell 520.
Each of the first plurality of seal strips 550, as described for
some embodiments herein, may have a curved outer diameter with a
curvature that is elliptical and/or wherein each of the first
plurality of seal strips have a curved inner diameter with a
curvature that is elliptical. In other embodiments, the seal strips
550 may be wider in regions where the bundle-to-shell gap is
larger. As the grid layout of the holes through the baffles may not
result in a circular pattern for the outermost holes, a seal strip
that may vary in width may provide better sealing. In some
embodiments, the width may be achieved by varying an elliptical
curvature of each of the inner and outer diameters of the seal
strips. In other embodiments, the width may be varied
systematically, such as to match a profile gap or provide a
consistent profile gap between the inner diameter of the seal
strips to each of the respective tubes. Similarly, a depth of the
seal strips may be varied. Thus, in various embodiments, each of
the first plurality of seal strips may have a width, outer diameter
minus inner diameter, that varies along a length, first end to
second end, of the seal strip, and/or each of the first plurality
of seal strips may have a depth, proximal side to distal side, that
varies along the width or the length of the seal strip
Additionally, in one or more embodiments, a number of the first
plurality of seal strips 550 per 360.degree. rotation about the
longitudinal axis 521 may be a multiple of a number of baffles per
360.degree. rotation about the longitudinal axis 521. Further, a
number of the first plurality of seal strips 550 disposed between a
baffle 540 and a corresponding, successive baffle 540 that is a
full 360.degree. rotation from the baffle 540 may be equal for all
baffles 540 in the plurality of baffles 540. For example, in one or
more embodiments, there may be four baffles 540 per 360.degree.
rotation about the longitudinal axis 521, and there may be four of
the first plurality of seal strips 550 per 360.degree. rotation
about the longitudinal axis 521 such that there is one of the first
plurality of seal strips 550 per baffle 540 per 360.degree.
rotation about the longitudinal axis 521. In other embodiments,
there may be four baffles 540 per 360.degree. rotation about the
longitudinal axis 521, and there may be eight of the first
plurality of seal strips 550 per 360.degree. rotation about the
longitudinal axis 521 such that there are two of the first
plurality of seal strips 550 per baffle 540 per 360.degree.
rotation about the longitudinal axis 521. The number of the first
plurality of seal strips 550 per 360.degree. rotation about the
longitudinal axis 521 may be dependent on the size of the inner
surface 525 of the shell 520, the number of the plurality of tubes
530 disposed within the heat exchanger, and the distance 534
between the outer diameters 535 of the plurality of tubes 530. In
one or more embodiments, there may be one of the first plurality of
seal strips 550 disposed within the shell 520 for every eight to
ten rows of the plurality of tubes 530 disposed within the heat
exchanger 500.
Furthermore, referring to FIG. 5A, in one or more embodiments, at
least one of the first plurality of seal strips 550 may be coupled
to a proximal side 546 of the baffle 540 and at least one of the
first plurality of seal strips 550 may be coupled to a distal side
547 of the baffle 540. Additionally, in one or more embodiments,
each of the first plurality of seal strips 550 that is coupled to
the distal side 547 of each of the plurality of baffles 540 may be
offset rotationally about the longitudinal axis 521 of the shell
520 from each of the first plurality of seal strips 550 that is
coupled to the proximal side 546 of each of the plurality of
baffles 540. In one or more embodiments, the rotationally offset
seal strips 550 may follow a predetermined pattern along an entire
length of the heat exchanger 500. Further, while rotationally
offset adjacent seal strips 550 are shown in FIG. 5A, in one or
more embodiments, the adjacent seal strips 550 may be
longitudinally aligned along an entire length of the heat
exchanger. Additionally, in one or more embodiments, the first
plurality of seal strips 550 may be formed of steel.
In yet other embodiments, the first plurality of seal strips 550
may be disposed such that each of the first plurality of seal
strips 550 are substantially parallel (substantially parallel being
+/-1.degree. or another small manufacturing tolerance) to a
longitudinal axis of the heat exchanger. When parallel to the
longitudinal axis, each seal strip should be connected to a
proximal baffle 540 and a longitudinally adjacent distal baffle
540. As compared to the prior practice of including a hole for the
seal strip in each baffle plate and using a single, long seal strip
from one end of the exchanger to the other, it has been found that
individual seal strips between longitudinally adjacent baffles
provides for both better sealing and a reduced pressure drop. In
some embodiments, the seal strips connected to longitudinally
adjacent baffles may be circumferentially offset. For example, each
of the plurality of baffles may be connected to at least two seal
strips 550, including a distal seal strip 550 connected to a distal
side of a baffle, and a proximal seal strip 550 connected to a
proximal side of the same baffle, where the proximal seal strip is
circumferentially offset from the distal seal strip. In some
embodiments, the circumferential offset may be at least 10.degree.,
at least 15.degree., or at least 20.degree., but necessarily offset
by less than the total number of degrees of the respective
elliptical sector of the sector shaped baffle. The rotationally or
circumferentially offset seal strips may thus include one, two or
more seal strips connected to a proximal side of a baffle as well
as one, two or more seal strips connected to a distal side of a
baffle, where the number of seal strips connected to the distal and
proximal sides may be equal in some sectors and unequal in others.
In some embodiments, an equal number of seal strips may be coupled
to each baffle of the plurality of baffles. In other embodiments, a
seal strip may not be coupled to every baffle of the plurality of
baffles. For instance, where four baffles are used per 360.degree.
rotation, including quadrants A, B, C, and D, seal strips may only
be used in quadrants A and C or B and D, for example; in other
embodiments, seal strips may be used, for instance, every three
quadrants (successively A, D, C, B, A . . . ). The number and
placement of seal strips may depend upon the sealing and structural
requirements of a particular heat exchanger.
Referring now to FIGS. 6A-6D, portions of heat exchangers 600
according to several embodiments of the present disclosure are
shown. As discussed above with regard to FIGS. 5A-5E, in one or
more embodiments, a heat exchanger 600 may include a plurality of
elliptical sector-shaped baffles 640 and a first plurality of seal
strips 650 disposed between the baffles 640. The first plurality of
seal strips 650 may each be disposed between a first baffle 640 and
a corresponding, successive baffle 640 that is a full 360.degree.
rotation from the first baffle 640. Further, a first end 651 of
each of the first plurality of seal strips 650 may be coupled to a
distal side 647 of one of the plurality of baffles 640 between a
proximal radial edge 644 and a distal radial edge 645, and a second
end 652 of each of the first plurality of seal strips 650 may be
coupled to a proximal side 646 of another of the plurality of
baffles 640 between the proximal radial edge 644 and the distal
radial edge 645. In one or more embodiments, the proximal radial
edge 644 of each baffle 640 may be the radial edge of the baffle
640 that is closest to an inlet of a shell of the heat exchanger
600, and the distal radial edge 645 of each baffle 640 may be the
radial edge of the baffle 640 that is farthest from the inlet of
the shell of the heat exchanger 600. Similarly, in one or more
embodiments, the proximal side 646 of each baffle 640 may be the
side of the baffle 640 that is closest to the inlet of the shell of
the heat exchanger 600, and the distal side 647 may be the side of
each baffle 640 that is farthest from the inlet of the shell of the
heat exchanger 600.
Referring to FIG. 6A, in one or more embodiments, each of the first
plurality of seal strips 650 may be disposed orthogonal to both the
distal side 647 of one baffle 640 and the proximal side 646 of
another baffle 640. In other embodiments, each of the plurality of
seal strips 650 may be disposed at an angle (not shown) from
orthogonal to the proximal side 646 of one baffle 640 and the
distal side 647 of the other baffle 640, and the angle may be from
greater than 0.degree. up to 80.degree..
Referring to FIG. 6B by way of example only, seal strips 650 may be
connected between a first baffle 640 and a second baffle 640 in the
same quadrant. Each of the plurality of seal strips may be disposed
at an angle from orthogonal to the proximal side 646 of the first
baffle 640, and the angle may be from greater than 45.degree. up to
80.degree. in a direction defined from the distal radial edge 645
to the proximal radial edge 644 of the second baffle 640. Further,
as discussed above, in other embodiments, the angle may be one of
from greater than 0.degree. up to 30.degree., from 15.degree. up to
45.degree., or from 15.degree. up to 30.degree.. Due to the
possible leakage of a first fluid between consecutive baffles of
the plurality of baffles 640, the direction of the first fluid flow
may vary slightly from the helical path formed by the plurality of
baffles 640. Further, due to this possible variance in the first
fluid flow direction, the angle of the seal strips 650 may vary
such that each of the first plurality of seal strips 650 may be
orthogonal to the helical first fluid flow direction.
Referring to FIG. 6C by way of example only, seal strips 650 may be
connected between a first baffle 640 in a first quadrant and a
second baffle 640 in an adjacent quadrant. Each of the plurality of
seal strips may be disposed at an angle from orthogonal to the
proximal side 646 of the first baffle 640, and the angle may be
from greater than 45.degree. up to 80.degree. in a direction
defined from the distal radial edge 645 to the proximal radial edge
644 of the second baffle 640. Further, as discussed above, in other
embodiments, the angle may be one of from greater than 0.degree. up
to 30.degree., from 15.degree. up to 45.degree., or from 15.degree.
up to 30.degree. in a direction defined from the distal radial edge
645 to the proximal radial edge 644 of the second baffle 640. Due
to the possible leakage of a first fluid between consecutive
baffles of the plurality of baffles 640, the direction of the first
fluid flow may vary slightly from the helical path formed by the
plurality of baffles 640. Further, due to this possible variance in
the first fluid flow direction, the angle of the seal strips 650
may vary such that each of the first plurality of seal strips 650
may be orthogonal to the helical first fluid flow direction.
In some embodiments, some seal strips 650 may be connected between
baffles 640 in the same quadrant, as illustrated in FIG. 6B, while
other seal strips 650 may be connected between baffles 640 in
adjacent quadrants, as illustrated in FIG. 6C.
While embodiments shown in FIGS. 6A-6C may include a plurality of
seal strips 650 that are all disposed at the same angle between one
baffle 640 and another baffle 640, referring to FIG. 6C, in one or
more embodiments, the seal strips 650 may be disposed at different
angles (not shown) within the heat exchanger. In other words,
referring to FIG. 6C, in one or more embodiments, one seal strip
650a of the plurality of seal strips 650 may be disposed orthogonal
to both the distal side 647 of one baffle 640 and the proximal side
646 of another baffle 640, and another seal strip 650b of the
plurality of seal strips 650 may be disposed at an angle from
orthogonal to the proximal side 646 of one baffle 640 and the
distal side 647 of the other baffle 640 in which the angle may be
from greater than 0.degree. up to 80.degree.. Thus, while in one or
more embodiments, all of the seal strips 650 may be disposed
between baffles with the same angular disposition, in other
embodiments, a combination of seal strips 650 of different angular
dispositions may be used. Further, while in one or more
embodiments, seal strips 650a of a first angular disposition may be
used between the baffles 640 of the first several rotations about
the longitudinal axis and seal strips 650b of a second angular
disposition may be used between the baffles 640 of the remaining
rotations about the longitudinal axis, in other embodiments,
different patterns of seal strips 650a of a first angular
disposition and seal strips 650b of a second angular disposition
may be used. Furthermore, in one or more embodiments, seal strips
of more than two angular dispositions may be used throughout the
heat exchanger in different patterns. In some embodiments, both the
angular dispositions of the seal strips and the quadrants between
which the seal strips are arranged may vary within a heat
exchanger.
Referring now to FIG. 7, a portion of a heat exchanger 700
according to one or more embodiments of the present disclosure is
shown. In one or more embodiments, a heat exchanger 700 may include
a shell (not shown) through which a first fluid is passed, a
plurality of axially extending tubes 730 through which a second
fluid is passed, a plurality of elliptical sector-shaped baffles
740, and a first plurality of seal strips 750 disposed between the
baffles 740. The shell may include an inlet (not shown) and an
outlet (not shown) between which the first fluid may pass within
the shell. Further, the plurality of tubes 730, the plurality of
baffles 740, and the first plurality of seal strips 750 may be
disposed within the shell.
Referring to FIG. 7, similar to heat exchangers discussed above, in
one or more embodiments, the plurality of baffles 740 may be
disposed such that successive baffles 740 are positioned at an
angle from a line that is normal to a longitudinal axis (not shown)
of the shell. In one or more embodiments, the baffles 740 may be
coupled about the longitudinal axis, and the successive baffles 740
may be rotationally and longitudinally offset from each other such
that a helical pattern is formed. The rotational offset between
successive baffles 740 may be such that at least a proximal radial
edge 744 of one baffle 740 overlaps a distal radial edge 745 of an
adjacent baffle 740 in a longitudinal direction. In one or more
embodiments, the proximal radial edge 744 of each baffle 740 may be
the radial edge of the baffle 740 that is closest to the inlet of
the shell of the heat exchanger 700, and the distal radial edge 745
of each baffle 740 may be the radial edge of the baffle 740 that is
farthest from the inlet of the shell of the heat exchanger 700.
Further, as discussed above, in one or more embodiments, there may
be an equal number of baffles 740 per 360.degree. rotation about
the longitudinal axis about which the baffles 740 are disposed.
Still referring to FIG. 7, in one or more embodiments, the baffles
740 may be elliptical sector-shaped. Each of the baffles 740 may
have an outer circumferential edge 743, and each outer
circumferential edge 743 may be spaced apart from the outer
circumferential edge 743 of an adjacent baffle 740. Each of the
baffles 740 may also include the proximal radial edge 744 at one
end of the outer circumferential edge 743 and the distal radial
edge 745 at the other end of the outer circumferential edge 743
such that the elliptical sector-shaped baffles 740 are defined by
the outer circumferential edge 743, the proximal radial edge 744,
and the distal radial edge 745. Furthermore, each of the baffles
740 may have a proximal side 746 and a distal side 747 that are
opposite of each other as well as a plurality of spaced apart holes
(not shown) that extend through the baffles 740 from the proximal
side 746 to the distal side 747. In one or more embodiments, the
proximal side 746 of each baffle 740 may be the side of the baffle
740 that is closest to the inlet of the shell of the heat exchanger
700, and the distal side 747 may be the side of each baffle 740
that is farthest from the inlet of the shell of the heat exchanger
700. Further, in one or more embodiments, one tube 730 of the
plurality of axially extending tubes 730 may pass through holes in
the baffles 740. Therefore, as discussed above, the plurality of
tubes 730 may extend axially along an entire length of a heat
exchanger 700, and each of the tubes 730 may be supported by
multiple baffles 740 spaced equally along a length of the tube 730.
Furthermore, a distance between outer diameters of each of the
tubes 730 that are disposed in each of the holes may be consistent
across the entirety of the plurality of tubes 730.
Further, referring to FIG. 7, in one or more embodiments, a first
plurality of seal strips 750 may each be disposed between a first
baffle 740 and a corresponding, successive baffle 740 that is a
full 360.degree. rotation from the first baffle 740. Furthermore,
each of the first plurality of seal strips 750 may be disposed
radially between the plurality of tubes 730 and a diameter of an
inner surface of the shell. As discussed above, in one or more
embodiments, each of the first plurality of seal strips 750 may be
coupled to each of the first baffle 740 and the corresponding,
successive baffle 740. In one or more embodiments, the first
plurality of seal strips 750 may be disposed such that each of the
first plurality of seal strips 750 are orthogonal to the helical
first fluid flow direction within the shell of the heat exchanger
700. Further, in one or more embodiments, a first end 751 of each
of the first plurality of seal strips 750 may be coupled to the
distal side 747 of one of the plurality of baffles 740 between the
proximal radial edge 744 and the distal radial edge 745, and a
second end 752 of each of the first plurality of seal strips 750
may be coupled to the proximal side 746 of another of the plurality
of baffles 740 between the proximal radial edge 744 and the distal
radial edge 745.
As discussed above, in one or more embodiments, each of the first
plurality of seal strips 750 may be disposed orthogonal to both the
distal side 747 of one baffle 740 and the proximal side 746 of
another baffle 740. Further, in other embodiments, each of the
plurality of seal strips 750 may be disposed at an angle (not
shown) from orthogonal to the proximal side 746 of one baffle 740
and the distal side 747 of the other baffle 740; the angle may be
from greater than 0.degree. up to 80.degree.. In further
embodiments, the angle may be one of from greater than 0.degree. up
to 30.degree., from 15.degree. up to 45.degree., from 45.degree. up
to 80.degree., or from 15.degree. up to 30.degree.. Due to the
possible leakage of a first fluid between consecutive baffles of
the plurality of baffles 740, the direction of the first fluid flow
may vary slightly from the helical path formed by the plurality of
baffles 740. Further, due to this possible variance in the first
fluid flow direction, the angle of the seal strips 750 may vary
such that each of the first plurality of seal strips 750 may be
orthogonal to the helical first fluid flow direction. The baffles
740 may be arranged in quadrants. In some embodiments, seal strips
750 may be connected between baffles 740 located in the same
quadrant. In some embodiments, seal strips 750 may be connected
between baffles 740 located in adjacent quadrants. In some
embodiments, seal strips 750 may be connected between both baffles
740 located in the same quadrant and baffles 740 located in
adjacent quadrants.
Furthermore, referring to FIG. 7, in one or more embodiments, each
of the first plurality of seal strips 750 may have a substantially
similar structure to the first plurality of seal strips as
described above with regard to FIGS. 5A-5E and 6A-6D. Therefore,
the first plurality of seal strips 750 may have a curved inner
surface and a curved outer surface. In one or more embodiments, the
curved outer surface of each seal strip 750 may be disposed
substantially proximate the inner surface of the shell. Further, in
one or more embodiments, the curved outer surface of one or more of
the seal strips 750 may contact the inner surface of the shell.
Additionally, a curvature of the curved outer surface of the seal
strips 750 may be elliptical in shape and may match a curvature of
the inner surface of the shell.
Furthermore, in one or more embodiments, a curvature of the curved
inner surface of each of the first plurality of seal strips 750 may
be elliptical in shape and the curvature of the inner surface may
be different than the curvature of the outer surface of each of the
first plurality of seal strips 750. In other words, in one or more
embodiments, the curvature of the inner surface of each seal strip
750 may match a curvature of an imaginary cylinder with a diameter
equal to the diameter of the inner surface of the shell minus a
radial width of the seal strip 750. Further, the inner surface of
each of the first plurality of seal strips 750 may be spaced from
the outer diameter of a closest tube 730 of the plurality of
axially extending tubes 730 by a distance. The distance between the
inner surface of the seal strips 750 and the outer diameter of the
closest tube 730 may be equal to the distance between the outer
diameters of two adjacent tubes 730. Furthermore, in one or more
embodiments, the first plurality of seal strips 750 may be angled
from the outer surface to the inner surface by an angle from a line
orthogonal to the shell in a direction of the first fluid flow.
Further, the first plurality of seal strips 750 may have a
thickness that varies depending on the diameter of the inner
surface of the shell.
Still referring to FIG. 7, in one or more embodiments, at least one
of the first plurality of seal strips 750 may be coupled to a
proximal side 746 of the baffle 740 and at least one of the first
plurality of seal strips 750 may be coupled to a distal side 747 of
the baffle 740. Additionally, in one or more embodiments, each of
the first plurality of seal strips 750 that is coupled to the
distal side 747 of each of the plurality of baffles 740 may be
longitudinally aligned with each of the first plurality of seal
strips 750 that is coupled to the proximal side 746 of each of the
plurality of baffles 740 in a direction that is parallel to the
longitudinal axis of the shell of the heat exchanger 700. As
discussed above, in one or more embodiments, a number of the first
plurality of seal strips 750 disposed between a baffle 740 and a
corresponding, successive baffle 740 that is a full 360.degree.
rotation from the baffle 740 may be equal for all baffles 740 in
the plurality of baffles 740, and thus, a number of the first
plurality of seal strips 750 per 360.degree. rotation about the
longitudinal axis may be a multiple of the number of baffles 740
per 360.degree. rotation about the longitudinal axis.
Referring now to FIG. 8, a portion of a heat exchanger 800
according to one or more embodiments of the present disclosure is
shown. In one or more embodiments, a heat exchanger 800 may include
a shell (not shown) through which a first fluid is passed, a
plurality of axially extending tubes 830 through which a second
fluid is passed, a plurality of elliptical sector-shaped baffles
840, a first plurality of seal strips 850 disposed between the
baffles 840, and a second plurality of seal strips 860 disposed
between the baffles 840. The shell may include an inlet (not shown)
and an outlet (not shown) between which the first fluid may pass
within the shell. Further, the plurality of tubes 830, the
plurality of baffles 840, the first plurality of seal strips 850,
and the second plurality of seal strips 860 may be disposed within
the shell.
Still referring to FIG. 8, similar to heat exchangers discussed
above, in one or more embodiments, the plurality of baffles 840 may
be disposed such that successive baffles 840 are positioned at an
angle from a line that is normal to a longitudinal axis (not shown)
of the shell. In one or more embodiments, the baffles 840 may be
coupled about the longitudinal axis, and the successive baffles 840
may be rotationally and longitudinally offset from each other such
that a helical pattern is formed. The rotational offset between
successive baffles 840 may be such that at least a proximal radial
edge 844 of one baffle 840 overlaps a distal radial edge 845 of an
adjacent baffle 840 in a longitudinal direction. Further, the
longitudinal offset of the overlapping proximal radial edge 844 and
distal radial edge 845 between successive baffles 840 may create a
gap 870 between the proximal radial edge 844 and the distal radial
edge 845 through which a first fluid flow may be able to travel. In
one or more embodiments, the proximal radial edge 844 of each
baffle 840 may be the radial edge of the baffle 840 that is closest
to the inlet of the shell of the heat exchanger 800, and the distal
radial edge 845 of each baffle 840 may be the radial edge of the
baffle 840 that is farthest from the inlet of the shell of the heat
exchanger 800. Further, as discussed above, in one or more
embodiments, there may be an equal number of baffles 840 per
360.degree. rotation about the longitudinal axis about which the
baffles 840 are disposed.
Further, referring to FIG. 8, in one or more embodiments, the
baffles 840 may be elliptical sector-shaped. Each of the baffles
840 may have an outer circumferential edge 843, and each outer
circumferential edge 843 may be spaced apart from the outer
circumferential edge 843 of an adjacent baffle 840. Each of the
baffles 840 may also include the proximal radial edge 844 at one
end of the outer circumferential edge 843 and the distal radial
edge 845 at the other end of the outer circumferential edge 843
such that the elliptical sector-shaped baffles 840 are defined by
the outer circumferential edge 843, the proximal radial edge 844,
and the distal radial edge 845. Furthermore, each of the baffles
840 may have a proximal side 846 and a distal side 847 that are
opposite of each other as well as a plurality of spaced apart holes
(not shown) that extend through the baffles 840 from the proximal
side 846 to the distal side 847. In one or more embodiments, the
proximal side 846 of each baffle 840 may be the side of the baffle
840 that is closest to the inlet of the shell of the heat exchanger
800, and the distal side 847 may be the side of each baffle 840
that is farthest from the inlet of the shell of the heat exchanger
800. Further, in one or more embodiments, one tube 830 of the
plurality of axially extending tubes 830 may pass through each of
the holes in the baffles 840. Therefore, as discussed above, the
plurality of tubes 830 may extend axially along an entire length of
a heat exchanger 800, and each of the tubes 830 may be supported by
multiple baffles 840 spaced equally along a length of the tube 830.
Furthermore, a distance between outer diameters of each of the
tubes 830 that are disposed in each of the holes may be consistent
across the entirety of the plurality of tubes 830.
Furthermore, referring to FIG. 8, in one or more embodiments, a
first plurality of seal strips 850 may each be disposed between a
first baffle 840 and a corresponding, successive baffle 840 that is
a full 360.degree. rotation from the first baffle 840. Furthermore,
each of the first plurality of seal strips 850 may be disposed
radially between the plurality of tubes 830 and a diameter of an
inner surface of the shell. As discussed above, in one or more
embodiments, each of the first plurality of seal strips 850 may be
coupled to each of the first baffle 840 and the corresponding,
successive baffle 840. In one or more embodiments, the first
plurality of seal strips 850 may be disposed such that each of the
first plurality of seal strips 850 is orthogonal to the helical
first fluid flow direction within the shell of the heat exchanger
800. Further, in one or more embodiments, a first end 851 of each
of the first plurality of seal strips 850 is coupled to the distal
side 847 of one of the plurality of baffles 840 between the
proximal radial edge 844 and the distal radial edge 845, and a
second end 852 of each of the first plurality of seal strips 850 is
coupled to the proximal side 846 of another of the plurality of
baffles 840 between the proximal radial edge 844 and the distal
radial edge 845.
As discussed above, in one or more embodiments, each of the first
plurality of seal strips 850 may be disposed orthogonal to both the
distal side 847 of one baffle 840 and the proximal side 846 of
another baffle 840. Further, in other embodiments, each of the
plurality of seal strips 850 may be disposed at an angle (not
shown) from orthogonal to the proximal side 846 of one baffle 840
and the distal side 847 of another baffle 850; the angle may be
from greater than 0.degree. up to 80.degree.. In further
embodiments, the angle may be one of from greater than 0.degree. up
to 30.degree., from 15.degree. up to 45.degree., from 45.degree. up
to 80.degree., or from 15.degree. up to 30.degree.. Due to the
possible leakage of a first fluid between consecutive baffles of
the plurality of baffles 840, the direction of the first fluid flow
may vary slightly from the helical path formed by the plurality of
baffles 840. Further, due to this possible variance in the first
fluid flow direction, the angle of the seal strips 850 may vary
such that each of the first plurality of seal strips 850 may be
orthogonal to the helical first fluid flow direction.
The baffles 740 may be arranged in quadrants. In some embodiments,
seal strips 750 may be connected between baffles 740 located in the
same quadrant. In some embodiments, seal strips 750 may be
connected between baffles 740 located in adjacent quadrants. In
some embodiments, seal strips 750 may be connected between both
baffles 740 located in the same quadrant and baffles 740 located in
adjacent quadrants.
Additionally, referring to FIG. 8, in one or more embodiments, each
of the first plurality of seal strips 850 may have a substantially
similar structure to the first plurality of seal strips as
described above with regard to FIGS. 5A-7. Therefore, the first
plurality of seal strips 850 may have a curved inner surface and a
curved outer surface. Further, in one or more embodiments, at least
one of the first plurality of seal strips 850 may be coupled to a
proximal side 846 of the baffle 840 and at least one of the first
plurality of seal strips 850 may be coupled to a distal side 847 of
the baffle 840. Additionally, in one or more embodiments, each of
the first plurality of seal strips 850 that is coupled to the
distal side 847 of each of the plurality of baffles 840 may be
longitudinally aligned with each of the first plurality of seal
strips 850 that is coupled to the proximal side 846 of each of the
plurality of baffles 840 in a direction that is parallel to the
longitudinal axis of the shell of the heat exchanger 800. Further,
as discussed above, in one or more embodiments, a number of the
first plurality of seal strips 850 disposed between a baffle 840
and a corresponding, successive baffle 840 that is a full
360.degree. rotation from the baffle 840 may be equal for all
baffles 840 in the plurality of baffles 840, and thus, a number of
the first plurality of seal strips 850 per 360.degree. rotation
about the longitudinal axis may be a multiple of the number of
baffles per 360.degree. rotation about the longitudinal axis.
Still referring to FIG. 8, each of a second plurality of seal
strips 860 may be disposed between one of the baffles 840 and a
successive baffle 840 within the gap 870 formed between the
proximal side 846 of the one of the baffles 840 and the distal side
847 of the successive baffle 840 in a region in which the distal
radial edge 845 of the one of the baffles 840 overlaps with the
proximal radial edge 844 of the successive baffle 840. Further,
each of the second plurality of seal strips 860 may be coupled to
the baffles 840 in a direction that is parallel to the longitudinal
axis of the shell of the heat exchanger 800, and the second
plurality of seal strips 860 may be disposed radially between the
shell and the plurality of tubes 830. Furthermore, each of the
second plurality of seal strips 860 may have a first end 861 that
may be coupled proximate to the proximal radial edge 844 of the
distal side 847 of one of the plurality of baffles 840 and a second
end 862 that may be coupled proximate to the distal radial edge 845
of the proximal side 846 of another of the plurality of baffles.
Additionally, in one or more embodiments, each of the second
plurality of seal strips 860 may be trapezoidal-shaped with an
inner surface 863 and an outer surface 864. The inner surface 863
of each of the second plurality of seal strips 860 may be spaced
from an outer diameter of a closest tube 830 of the plurality of
axially extending tubes 830 by a distance that may be equal to the
distance between outer diameters of two adjacent tubes 830 of the
plurality of axially extending tubes 830. Further, in one or more
embodiments, a number of the second plurality of seal strips 860
disposed between a baffle 840 and a successive baffle 840 in the
gap 870 formed by the region of overlap between the baffles 840 may
be equal to the number of baffles per 360.degree. rotation about
the longitudinal axis.
Referring now to FIG. 9, a heat exchanger 900 according to one or
more embodiments of the present disclosure is shown. FIG. 9
illustrates a heat exchanger having a double helix flow pattern,
which may include strips as described above between the helices.
While the strips are not illustrated for ease of understanding the
flow pattern, the description below is inclusive of the strips and
illustrative of how the strips may be incorporated into a heat
exchanger having multiple helical flow paths.
In one or more embodiments, a heat exchanger 900 may include a
shell 920 through which a first fluid is passed, a plurality of
axially extending tubes (not shown) through which a second fluid is
passed, a first plurality of elliptical sector-shaped baffles 940,
a second plurality of elliptical sector-shaped baffles 980
longitudinally offset from the first plurality of baffles 940, a
first plurality of seal strips (not shown) each disposed between a
first baffle 940 and a second baffle 980, and a second plurality of
seal strips 960 disposed between the baffles 940. The shell may
include an inlet 928 and an outlet (not shown) between which the
first fluid may pass within the shell. Further, the plurality of
tubes, the first plurality of baffles 940, the second plurality of
baffles 980, the first plurality of seal strips, and the second
plurality of seal strips may be disposed within the shell 920.
Still referring to FIG. 9, similar to heat exchangers discussed
above, in one or more embodiments, the first plurality of baffles
940 may be disposed such that successive first baffles 940 are
positioned at an angle from a line that is normal to a longitudinal
axis 921 of the shell 920. In one or more embodiments, the first
plurality of baffles 940 may be coupled about the longitudinal axis
920, and the successive first baffles 940 may be rotationally and
longitudinally offset from each other such that a helical pattern
is formed. The rotational offset between successive first baffles
940 may be such that at least a first radial edge (not shown) of
one first baffle 940 overlaps a second radial edge (not shown) of
an adjacent first baffle 940 in a longitudinal direction. Further,
the longitudinal offset of the overlapping first radial edge and
second radial edge between successive first baffles 940 may create
a gap between the first radial edge and the second radial edge
through which a first fluid flow may be able to travel. Further, as
discussed above, in one or more embodiments, there may be an equal
number of the first plurality of baffles 940 per 360.degree.
rotation about the longitudinal axis 921 about which the first
plurality of baffles 940 are disposed.
Similarly, the second plurality of baffles 980 may be disposed such
that successive second baffles 980 are positioned at an angle from
a line that is normal to the longitudinal axis 921 of the shell
920. In one or more embodiments, the second plurality of baffles
980 may be coupled about the longitudinal axis 921, and the
successive second baffles 980 may be rotationally and
longitudinally offset from each other such that a helical pattern
substantially identical to the helical pattern of the first
plurality of baffles 940 is formed. The rotational offset between
successive second baffles 980 may be such that at least a first
radial edge (not shown) of one second baffle 980 overlaps a second
radial edge (not shown) of an adjacent second baffle 980 in a
longitudinal direction. Further, the longitudinal offset of the
overlapping first radial edge and second radial edge between
successive second baffles 980 may be the same as the longitudinal
offset of the first baffles 940 and may create the same gap between
the first radial edge and the second radial edge through which a
first fluid flow may be able to travel. Further, as discussed
above, in one or more embodiments, there may be an equal number of
the second plurality of baffles 980 per 360.degree. rotation about
the longitudinal axis 921 about which the second plurality of
baffles 980 are disposed. Additionally, the second plurality of
baffles 980 may be longitudinally offset from the first plurality
of baffles 940 such that the flow path between successive rotations
of first baffles 920 is separated into two separate flow paths. In
one or more embodiments, the second plurality of baffles may be
longitudinally offset from the first plurality of baffles by half
of a distance between first baffles 940 that are a 360.degree.
rotation from each other.
Further, in one or more embodiments, each of the first plurality of
baffles 940 and the second plurality of baffles 980 may be
elliptical sector-shaped. Each of the baffles 940, 980 may have an
outer circumferential edge (not shown), and each outer
circumferential edge may be spaced apart from the outer
circumferential edge of an adjacent baffle 940, 980. Each of the
baffles 940, 980 may also include the first radial edge at one end
of the outer circumferential edge and the second radial edge at the
other end of the outer circumferential edge such that the
elliptical sector-shaped baffles 940, 980 are defined by the outer
circumferential edge, the first radial edge, and the second radial
edge. Furthermore, each of the baffles 940, 980 may have a first
side (not shown) and a second side (not shown) that are opposite of
each other as well as a plurality of spaced apart holes (not shown)
that extend through the baffles 940, 980 from the first side to the
second side. In one or more embodiments, each first baffle 940 may
be aligned with an adjacent second baffle 980 such that the holes
of each first baffle 940 aligns with the holes of the adjacent
second baffle 980 and one tube of the plurality of axially
extending tubes may pass through each of the holes in the baffles
940, 980. Therefore, as discussed above, the plurality of tubes may
extend axially along an entire length of a heat exchanger 900, and
each of the tubes may be supported by multiple baffles of each of
the first plurality of baffles 940 and the second plurality of
baffles 980. Furthermore, a distance between outer diameters of
each of the tubes that are disposed in each of the holes may be
consistent across the entirety of the plurality of tubes.
Furthermore, in one or more embodiments, a first plurality of seal
strips may each be disposed between a first baffle of the first
plurality of baffles 940 and a corresponding, adjacent baffle of
the second plurality of baffles 940 that is aligned with the first
baffle of the first plurality of baffles 940. In other words, each
of the first plurality of seal strips may be coupled between one of
the first side and the second side of one of the first plurality of
baffles 940 and the corresponding first side or second side of one
of the second plurality of baffles 980. Additionally, each of the
first plurality of seal strips may be disposed within the shell 920
of the heat exchanger 900 as described above with regard to other
embodiments, and each of the first plurality of seal strips may
have a substantially similar structure to the first plurality of
seal strips as described above with regard to other embodiments.
Further, each of a second plurality of seal strips may be disposed
between one of the first plurality of baffles 940 and a successive
baffle of the first plurality of baffles 940 and between one of the
second plurality of baffles 980 and a successive baffle of the
second plurality of baffles 980 within the gaps formed between the
first side of the one of the baffles 940, 980 and the second side
of the successive baffle 940, 980 in a region in which the first
radial edge of the one of the baffles 940, 980 overlaps with the
second radial edge of the successive baffle 940, 980. Further, each
of the second plurality of seal strips may be disposed within the
shell 920 of the heat exchanger 900 as described above with regard
to other embodiments, and each of the second plurality of seal
strips may have a substantially similar structure to the second
plurality of seal strips as described above with regard to other
embodiments.
Embodiments disclosed herein are also directed toward methods of
assembling of a heat exchanger. The method may include providing a
center rod having a longitudinal axis and mounting a plurality of
elliptical sector-shaped baffles to the center rod at an angle to
the longitudinal axis of the center rod such that a helical pattern
is formed by the plurality of baffles. Each of the plurality of
baffles may include: an outer circumferential edge longitudinally
spaced apart from the outer circumferential edge positions of the
rest of the plurality of baffles; a proximal radial edge spaced
from a distal radial edge; a proximal side opposite from a distal
side; and a plurality of spaced apart holes. A plurality of axially
extending tubes may be disposed into the plurality of spaced apart
holes of each of the plurality of baffles, wherein the plurality of
axially extending tubes are configured to carry a second fluid.
The method may further include coupling a first plurality of seal
strips having a first end and a second end radially between the
shell and the plurality of axially extending tubes. Coupling of the
first plurality of seal strips may include: coupling the first end
of each of the first plurality of seal strips to the distal side of
one of the plurality of baffles; and coupling the second end of
each of the first plurality of seal strips to the proximal side of
another of the plurality of baffles. Each of the first plurality of
seal strips is disposed either: orthogonal to both the distal side
of the one of the plurality of baffles and the proximal side of the
other of the plurality of baffles; or at an angle from orthogonal
to the proximal side of one of the plurality of baffles and the
distal side of another of the plurality of baffles, wherein the
angle is from greater than 0.degree. up to 80.degree.. The
assembled center rod, plurality of baffles, plurality of axially
extending tubes, and first plurality of seal strips may then be
disposed within a shell that is configured to receive a first
fluid.
The coupled first plurality of seal strips have an inner diameter
and an outer diameter. Coupling the first plurality of seal strips
may include angling the coupled first plurality of seal strips from
the outer diameter to the inner diameter by an angle from
orthogonal to the shell in the direction defined from the proximal
radial edge to the distal radial edge of the one of the plurality
of baffles.
Coupling the first plurality of seal strips may further include
spacing an inner diameter of each of the first plurality of seal
strips from an outer diameter of a closest tube of the plurality of
axially extending tubes by a distance that is equal to a distance
between outer diameters of two adjacent tubes of the plurality of
axially extending tubes. Coupling the first plurality of seal
strips may also include rotationally offsetting each of the first
plurality of seal strips coupled to the distal side of each of the
plurality of baffles from each of the plurality of seal strips
coupled to the proximal side of each of the plurality of
baffles.
The method of assembly may also include in some embodiments
coupling a second plurality of seal strips having a first end and a
second end radially between the shell and the plurality of axially
extending tubes. Coupling the second plurality of seal strips may
include: coupling the first end of each of the second plurality of
seal strips to the distal radial edge of the distal side of one of
the plurality of baffles; and coupling the second end of each of
the second plurality of seal strips to the proximal radial edge of
the proximate side of another of the plurality of baffles, wherein
each of the second plurality of seal strips extends parallel to the
longitudinal axis of the shell.
The heat exchanger according to one or more embodiments of the
present disclosure that has seal strips disposed orthogonal to each
of a plurality of baffles such that the seal strips are orthogonal
to a direction of flow of a first fluid provides many benefits over
conventional heat exchangers and other helically-baffled heat
exchangers. For example, seal strips disposed orthogonal to each of
the baffles may allow for a lower pressure drop over the entire
length of the heat exchanger than heat exchangers that include seal
strips that are disposed parallel to a longitudinal axis of the
heat exchanger. Further, by way of example, seal strips disposed
orthogonal to a direction of the first fluid flow and at an angle
such that the first fluid flow is directed back towards a plurality
of tubes carrying a second fluid may allow for less of the first
fluid to bypass the plurality of tubes than seal strips that are
disposed parallel to a longitudinal axis of the heat exchanger.
Furthermore, by way of example, in one or more embodiments,
radially offsetting the plurality of seal strips along a length of
the heat exchanger may allow for providing local heat transfer
enhancement to a greater number of the plurality of tubes.
Additionally, by way of example, a second plurality of seal strips
disposed adjacent to first and second radial edges of the baffles
may allow for less of the first fluid to leave the helical flow
path by leaking around the overlapping baffles. Therefore, the heat
exchanger according to one or more embodiments may allow for an
enhanced efficiency of heat transfer in addition to a lower cost of
manufacturing and a lower cost of maintenance compared to that of
conventional heat exchangers and other helically-baffled heat
exchangers.
Several surprising results are noted with respect to embodiments of
the present disclosure. First, experiments have shown that
conventional seal strips, not arranged as disclosed herein, have
little direct effect on heat transfer. In this way, they do not
significantly improve the efficiency of heat exchangers to which
they are added. In fact, these experiments have shown that
conventional seal strips can cause significant pressure drops
within heat exchangers, when compared to the same heat exchangers
with no seal strips. The pressure drop may reduce the efficiency of
heat transfer in the heat exchanger. This result is unexpected
because prior art teaches that any seal strip improves the
performance of a heat exchanger by preventing fluid from bypassing
the tube bundle. Current findings show however that the seal strips
arranged according to embodiments herein may improve the
performance of a heat exchanger.
Referring now to FIG. 10, heat exchanger performance of three heat
exchangers is compared: (1) a heat exchanger with no seal strips
(triangles), (2) a heat exchanger including four longitudinal seal
strips extending the length of the exchanger disposed through
respective through-holes in each baffle (squares), and (3) a heat
exchanger including angled seal strips, where the seal strips
direct flow in a manner to encourage helical flow of fluid through
the heat exchanger (circles). The experimental data is shown
including the Reynolds number on the bottom axis, a pressure-drop
conversion ratio on the left axis, and a Peclet number on the right
axis. As shown, for the given Reynolds number of the fluid flow,
the pressure-drop conversion ratio and Peclet numbers improve for
the seal strips arranged according to embodiments herein,
indicating a higher efficiency of conversion of pressure drop to
heat transfer.
Second, experiments have shown that seal strips connected such that
they oppose fluid flow, i.e. connected in reverse from what is
taught herein, can significantly reduce heat transfer. In some
experiments, these seal strips reduced heat transfer as much as 60%
relative to heat exchangers with no seal strips. This is surprising
because sealing of any type is expected to prevent bypassing and
thereby improve heat transfer. These results demonstrate however,
that not only must bypassing be prevented, but significant pressure
drops also must be avoided, in order to improve the heat transfer
in a heat exchanger. Accordingly, the specific arrangement and
orientation of seal strips taught herein is important in achieving
improved heat transfer.
Third, experiments have shown that seal strips connected as
disclosed herein can increase heat transfer without causing
significant pressure drops. These seal strips are connected to
encourage helical flow of fluid through the heat exchanger. This is
unexpected because prior art teaches that any sealing causes a
pressure drop penalty of approximately 30%-50%. Therefore, the
results of the present disclosure are more significantly positive
than would have been expected based on the prior art, because they
provide improved heat transfer without a corresponding increased
pressure drop.
While the invention has been described with respect to a limited
number of embodiments, those skilled in the art, having benefit of
this disclosure, will appreciate that other embodiments can be
devised which do not depart from the scope of the invention as
disclosed herein. Accordingly, the scope of the invention should be
limited only by the attached claims.
* * * * *